Human Structure 703 HISTOLOGY LAB GUIDE - 2007

Monday & Wednesday 9 am, Friday 1 pm -- Lecture, Hostler Auditorium
Monday & Wednesday 10-12 am -- Lab, Room 4023

Instructors: You, the student
Dr Holly Ressetar . . . . .Room 4047 . . (293-1687) . . and Dept No. 293-2212 for all
Dr Gregory Konat. . . . . .Room 4016 . . (293-0594)
Dr William Beresford . . . . . Room 4003 . . (293-0589) Home phone 292-0083

Required Textbook:
Histology. A Text and Atlas by M.H. Ross, E.J. Reith, and L.J. Romrell, 4th OR 5th edition, Williams & Wilkins, Baltimore 2005.

Other resources:
"Histology Lab Assistant" On the Anatomy SBLC computers should be available as an icon

Histology Full-text by Beresford at http://wberesford.hsc.wvu.edu/histol.htm & Histology Powerpoints at the same site
 The local HSC version has separate chapters for printing each as needed.

The 703 Course site on SOLE http://sole.hsc.wvu.edu

A good online Atlas is at http://129.241.42/pathology/nlm_histology . . Other Atlases are listed in the Introduction to Histology Fulltext

The 35 mm slides, projected in the lecture to orient you for the lab, will be put in the lab a day or so after the lecture, along with a slide projector.

The Histo component is primarily a task-based independent exercise for you - to be competent in visual microscopic diagnosis, and in knowing the functional and some clinical correlates of what you recognize. The textbook was chosen thus for laboratory helpfulness, but also for relative brevity, and because one of the authors was for many years on the USMLE Anatomy sub-committee constructing Step I of the licensing examination. Using the book for review next year will be easier if you are already familiar with it. We expect you not 'to have learned it', but to have consulted it intelligently and extracted enough ideas and information to do well on the exams.

Clinical correlations . Our number of lectures relative to other basic sciences is few, so that we weave clinical significance into the presentations and exam questions instead of having clinicians visit.

General Objectives:
At the completion of this course the student should be able to

  1. describe some of the routine techniques used for the microscopic preparation of cells and tissues and explain the effects of these techniques on histological appearance;
  2. identify the structural components of cells at the light and electron microscopic levels;
  3. interpret the activities and properties of living cells based on the observation of fixed specimens;
  4. recognize examples of the basic tissue types for later application in organology and pathology;
  5. identify selected organs and their parts by examining stained sections with the light microscope and by examining electron micrographs in textbooks, and;
  6. correlate structure with function in all cells, tissues and organs studied (eye and ear will be studied later in Neurobioogy)

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                           HISTOLOGY SCHEDULE 

                                        
Jan.3 WEDNESDAY               4 THURSDAY      Anomalous first week
Intro & Cytology              Cytology II
Lab: Intro & Cell    
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     MONDAY                  WEDNESDAY                   FRIDAY
Jan 8 Epithelium I & II      10 Connective tissues I    12 Connective tissues II
Lab: Epithelium             Lab: Connective tissues  

15 HOLIDAY                17 Cartilage                   19 Assessment I 
                          Lab: Cartilage & Bone             Bone I		   

22  Osteogenesis          24  Muscle I                    26 Muscle II
    Neural tisue              Lab: Neural Tissue
Lab: Bone                

29 Lab: Muscle          31 Skin                   Feb. 2 HISTO REVIEW
  No Histo lecture         Lab: Skin

Feb. 5 & 6  EXAM I      7 No Histo Lecture           9 Circulatory system I 
                       
12 Circulatory II             14 Respiratory system      16 Urinary system I        
Lab: Circulatory               Lab: Respiratory	   

19 Urinary II             21 Male reproductive I            23 Female I
Lab: Urinary            Lab: male reproductive            Female repro
              20 Tues Assessment II  Another anomaly

26 Female repro II        28  No Histo                 March 2 HISTO REVIEW
   No histo lab		

5 & 6  EXAM II             7 Oral  & esophagus	        9   ROAD TRIP!
                           Lab: Oral & esophagus	    No need to get excited

12 Stomach & Gut         14 Liver & Pancreas              16  No Histo lecture
Lab: Stomach & gut      Lab: Liver & Pancreas

19 Endocrines & Blood         21  Hemopoiesis              23 No Histo lecture          
Lab: Blood & Endocrines     Lab: Blood & Endocrines 	
      March 20 Tues Assessment II  Another anomaly
 
26 Lymphoid organs I        28 Lymphoid organs II         2 No Histo lecture
Lab: Lymphoid I

April 2 HISTO  REVIEW         4 No Histo                   6   EASTER
	
9 & 10 EXAM III 

HS 303 Histology Laboratory: The basic agenda

1 Today we'll have a little theory about how microscope slides are made and marked for identification, and a quick review of the light microscope and its controls and use.

2 Then, we'll go to the lab, 4023, to find our assigned places with a key to the microscope locker and the drawer with the slide sets. (With the key is the number to unlock your Gross Anatomy locker, out in the hallway. Gross directions will be given this afternoon.)

3 The individual slide sets will be checked against an inventory (not all slides are present) and the completed inventory sheets handed in. [Another version of the inventory is at the back of this Lab Guide.]

4 Using a well-stained slide, we'll try using the microscope and getting binocular fusion of the images (not everyone will the first time).

5 We shall also try the microscope on some slides showing the less usual methods of tissue preparation, and we'll get some first impressions of how tissues and cells look with various staining methods. What one stains for is what one sees, and the picture is always a very partial one. The figures specified in the text-atlas give one an initial idea of what to expect. The standing assignment is to read in advance the chapter matching the lecture topic, at the least, to have read the text going with the plates. Other textbooks can substitute for Ross & Romrell.

6 Also on Wednesday, we shall start thinking about cells as the fundamental component of organ systems, and taking a preliminary look at them in some slides. However, the electron microscope (EM) is far better than the light microscope for seeing cell structure, so that here the `lab' exercise extends beyond lab time, being mostly one of your looking at cytology pictures in the textbook and atlases, and using the histology computer program (Histology Lab Assistant) in the SBLC.

7 On Monday, we'll start the first tissue - Epithelium, and the lab will involve searching designated slides for examples of what has been shown as 35-mm projected slides in the lecture. Read the `Epithelium' chapter and PowerPoints beforehand.

8 The point of a lab is to tackle messy reality rather than looking at pretty pre-packaged views. [You know the theory of cardiovascular and respiratory systems, but can you confidently do CPR?] Mixed in with, or at the end of, most lists of things to find in a lab session, are comments on how the material fails to connect with the theory. Skim through these comments before going systematically down the list. By the end of the Module, you will be competent in the skills of microscopy and intelligently reading slides, will appreciate the significance of cell and tissue structure for normal function and pathology, and should know enough to pass the boards.

9 The assessments and exams will have typical written questions - you will be provided with examples and can get them from previous years. The histology lab exam involves your going around microscopes and EM figures set up in the lab in numbered sequence, with just over a minute per station. Answer the question on the card. The kinds of question we ask are at the end of the Neural Tissues section Lab exam format. Frame your lab thinking, from the start, in terms of questions by reformatting the neural examples for each tissue.

10 After the first exam, life gets easier. (a) We are on organ systems, whose components and physiology you know. (b) The light microscope is operating at its most favorable, showing how tissues and special cells are organized to make up an organ. (c) We have left behind the initially difficult mixture of three levels of analysis - cytology, tissues, & organs - to concentrate on organs.

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TODAY's HISTO LAB PROCEDURES

On the 4th floor, straight back from the working elevator, go to the SBLC (Rm 4005) and LEAVE your winter coat there or in your locker (in the main lab, there are papers & keys on the desks that can get hidden or swept off, if coats are brought in today)

Take only your book-bag (& computer, if you have it with you) into 4023. Locate your place - labeled in alphabetical order from the far end of the lab. The last nine in the Class alphabetical order will find their places on the side benches. You will have sitting places in the lab, but this will be sorted out in the course of the morning.

Find the small key at your place and attach it to your key ring or something visible, when dropped in the snow. (Note: your key number does not match your microscope number.)

Use the key gently to open the top drawer at your place & take out the two small boxes of slides. Place them near the middle of the bench. Do not balance your slide box in the open drawer or leave it close to the edge of the bench. [The sound of a slide box hitting the floor is painful and expensive.]

Open the locker, and carefully lift out the microscope. Find the microscope-use directions (next two pages). Follow them with any well-stained slide. Ask us for help. [We will not issue oil for the X100 oil lens] Switch off the scope. Complete the receipt form.

Note the convention on slide numbering below. Check your slide boxes against the inventory. Leave the completed inventory form at your place.

KEY TO SLIDE LABELING:

                                                Slide set number:
                                                same as cabinet and
           Slide number    J-7        SET 33    microscope number

                           PARATHYROID          Tissue or organ
       Source of tissue    Human      
                           H & E                Stain

Students in places 59-94 have the older (better?) Leitz microscopes. These have an extra flip-up lens at the top of the condenser under the stage. This lens should be switched OUT for the X4 low-power objective, but very definitely switched INTO use for all other objectives. After a while you'll get the hang of this. Whatever `scope you have, try out one of the other kind between now and the first exam. The exam will be set up using both kinds, and for SOME stations you can use all the `scope controls

Now start the Histology Lab 1 exercise three pages ahead of here after the Schedule and Contents. It is not necessary for you to finish the Lab exercise today. In fact, since, after Histology Preparation Methods, it deals with Cells, it continues on to the first Exam.

Put your scope & slides away carefully. Lock the drawer & locker. About half of you share with a dental student. Please be considerate throughout the semester. Meaning, among other things: always put the slides back in the correct slots in the boxes; do not leave personal items - half-used suckers, toothbrushes, costly textbooks, etc - in the drawer or locker; and, if really needed, only good-humored notes to your unseen colleague, please.

You can use your access cards to get into the lab at any times, except Tuesday, Wednesday & Tuesday and Thursday 2-4, when the Dental students have class, or at their exam times. When our exams come around, we'll work to avoid any conflicting review times


LINKED CONTENTS Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . .v Introduction General Laboratory Directions . . . . . . . . . . . . . . . . .1 Tissue Preparation for Microscopy . . . . . . . . . . . . . . .2 Cells and Tissues General Structure of Cells . . . . . . . . . . . . . . . . . .3 Epithelial Tissues . . . . . . . . . . . . . . . . . . . . . .7 Cell Surface Specializations . . . . . . . . . . . . . . . . . 8 Neural Tissue . . . . . . . . . . . . . . . . . . . . . . . . 22 Connective Tissue . . . . . . . . . . . . . . . . . . . . . . .9 Muscle. . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Cartilage . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Bone . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Lab exam format . . . . . . . . . . . . . . . . . . . . . . . 24 Functional Systems Skin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Circulatory System . . . . . . . . . . . . . . . . . . . . . 26 Respiratory System. . . . . . . . . . . . . . . . . . . . . . 28 Urinary system. . . . . . . . . . . . . . . . . . . . . . . . 30 Male Reproductive System . . . . . . . . . . . . . . . . . . .46 Female Reproductive System . . . . . . . . . . . . . . . . . .44 Oral Structures . . . . . . . . . . . . . . . . . . . . . . . 43 Esophagus & Stomach . . . . . . . . . . . . . . . . . . . . . 37 Small & Large Intestines . . . . . . . . . . . . . . . . . . 39 Liver & Pancreas. . . . . . . . . . . . . . . . . . . . . . . 41 Endocrine Organs* . . . . . . . . . . . . . . . . . . . . . . 12 Blood & Hematopoiesis . . . . . . . . . . . . . . . . . . . . 34 Lymphoid Organs . . . . . . . . . . . . . . . . . . . . . . . 35 Glands. . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Appendix Slide List . . . . . . . . . . . . . . . . . . . . . . . . . .47

HUMAN STRUCTURE: HISTOLOGY LAB 1

NO SLIDES OR MICROSCOPES ARE TO LEAVE THE LAB AT ANY TIME! 1. MAINTENANCE OF SLIDES AND MICROSCOPES: Dirty slides and dirty microscope eyepieces and objectives make accurate anatomical observation difficult to impossible. Using only clean paper towel or tissue, clean lenses for each lab session and each slide before examining it. 2. SLIDE STORAGE: At the end of each laboratory period, return the slides neatly to the slide boxes and lock your slide collection (2 boxes) in the drawer containing the microscope. (Note: your key number does not match your microscope number.) YOUR ABILITY TO SEE CLEARLY WITH BINOCULAR VISION IN THE MICROSCOPE IS IMPORTANT IN THIS COURSE. IF, AFTER A WEEK OR SO, YOU HAVE DIFFICULTY WITH YOUR SCOPE OR YOUR VISION, TELL US Tissue Preparation and Cytology Start the exercise below. The slide A-1 of blood smear is last of the four on examples of preparation methods. The smear is difficult to focus on. It needs at least the medium-power X10 0bjective; and the glare has to be taken out of the view with the iris diaphragm on the condenser. In difficulty? Put up your hand and an instructor will help you. In this and future labs, do not get hung up on a slide. If you cannot get your question answered in a minute or so, go on to the next slide; and come back later, when the question can be answered. Remind yourself with a note by the item. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Tissue Preparation for Microscopy The following slides show examples of several methods of tissue preparation, used less often than sections Examine each first with the naked eye and then under low power on your microscope. References to figures in the text-atlas are given as Fig. or Plate #s in Ross et al.'s Histology Atlas 4th edition. A-9 Connective tissue spread - an example of a spread preparation (Fig 5.1) A-15 Bone - this is a dry ground specimen of bone (Plate 11. Fig 1) C-5 Nerve - a teased specimen of nerve (needs hunting for at low power) A-1 Blood smear (Fig 9.1) - this is an example of a smear preparation (needs the contrast improved, and the glare reduced, by partly closing the diaphragm on microscope condenser) Learn to recognize each of these special types of preparation. However, the majority of the slides are sections, made as described in the Intro and in the book. Most of our sections are made by imbedding the treated tissue in paraffin wax (like the string of a candle), although a few are embedded in plastic (like some souvenir paperweights). The sections, although very thin, do have some thickness, so it is necessary to use continually the microscope's fine focus control in order to see cells and fibers in their proper perspective. This is true of all types of cell and tissue preparations. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - General Structure of Cells The structures visible in a particular cell, when viewed with the light microscope, will depend upon the type of cell, the state of the cell at the time of fixation, the method of preparation and the optical properties of the microscope, including the magnification used. Examine cells with these aspects in mind. 1. General structure a. size and shape of cells b. relationship to surrounding cells c. prominence of plasma membrane d. specializations of the cell surface 2. The nucleus (or nuclei) a. number b. shape and relative size c. position within the cell d. general appearance (pale, dense) e. presence or absence, and number of nucleoli 3. Cytoplasm a. general appearance (homogeneous, granular) b. staining reaction c. presence of specific organelles and/or inclusions 4. Any activities of the cell that can be inferred from the observation of fixed specimens, e.g., phagocytosis of black dust particles by lung macrophages The following slides show examples of various cell structures and characteristics. Using your textbook, learn to find cells and their components. NOTE: It is not the intention of this exercise for you to learn to differentiate specific cells or tissues at this time, but rather to learn the general characteristics of cells which will aid you in identifying tissues and organs at a later time. The questions here are designed to improve your observational skills, not to quiz you on characteristics of specific tissues or organs. Appreciate that you are searching for very small elements in large masses of tissue. Cells only begin to acquire a visual identity under the high-dry (X40) magnification (the oil X100 lens would be better, but is too messy for now). Get used to scanning over the slide at low power, then checking at high or medium power. If there is no match, go back to low and scan some more. You will need an Atlas or Text-Atlas to help you get oriented. SLIDE E-29 This is an example of a routine hematoxylin and eosin (H&E) preparation of liver (Plate 61 Fig 1). Determine as much information as possible about the cells in this section. What color is the cytoplasm? What color are the nuclei? Are boundaries between individual cells visible? Note the size of the nucleus in relation to the size of the cell. The size of the cells has to be worked out from the spacing of the nuclei, assuming one nucleus per cell - not always the case in liver. E-32 This section of liver is stained to show glycogen granules red (see middle inset Fig on the cover of the textbook). Other cell details are not as clear as they were in the preceding slide. Do all of the cells have the same amount of glycogen? E-28 The stain used on this section of liver provides no new information about the cells, but here the extracellular (outside the cell) connective tissue fibers giving support within the liver are stained green. In the next three slides, note the variation in the shape of the cells specialized to perform specific functions. A-1 Observe the cells present in this smear preparation of blood (Fig 9.1). Do not attempt to identify specific blood cells at this time, although the distinction between the numerous orange red blood cells lacking nuclei and the rare white blood cells with nuclei is obvious. G-5 Locate the cartilage of the trachea (Fig 18.5 & Plate 67 Fig 2) and note the shape of the cells which are embedded in a firm extra-cellular matrix made by the cells. D-5 Compare slides D-5 and D-6. Slide D-5 is a standard H. & E. preparation of a lymph node. Slide D-6 is a lymph node that has been prepared using a special technique in which colloidal silver particles are deposited on supporting connective-tissue fibers that are unstained by the H&E stain. Fig 13.19 The silver coating renders the fibers visible with the light microscope and the fibers are said to be argyrophilic (silver-loving). Plate 36 Fig.3 is similar. Are cells, other than their nuclei, stained by the silver impregnation technique? Does either procedure by itself give the complete picture of the structure of a lymph node? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ARTIFACTS THIS TOPIC HAS AN IMPLICATION - The need for skepticism about what one sees in the slide. In examining any specimen with the microscope, it is important to keep in mind the possible occurrence of artifacts, which are imperfections in the specimen that are induced during processing. A-9 Unless the slide happens to be perfect, it will contain some large & long structures made up of a segmented arrangement of brown spots. These are rat hairs that came in contact with the tissue as it was being removed from under the rat's skin. The spread technique used in preparing this slide made it impossible to remove these extraneous hairs (not to be found in all specimens). G-6 Tissues generally shrink somewhat during their preparation, but not all tissues will shrink at the same rate. Unequal shrinkage in this section resulted in wrinkles and folds in the cartilage, which did not shrink as much as the surrounding soft tissue. Unequal shrinkage also results in false spaces around cells. Where there appear to be "empty" spaces in the cytoplasm, these are not holes, but usually are the spaces left behind when the fat/lipid material that the cells formerly contained was dissolved out during tissue processing. This is most obvious in fat cells, but affects other cells working a lot with lipids, e.g., sebaceous cells, adrenal cortical cells, etc. Poor technique may result in tears in the tissue, knife marks on the tissue, too much or too little stain, or large folds and wrinkles due to poor mounting of sections on slides. Bubbles of air or water may occur on the slide. Dirt is the most common artifact, and you can correct this by cleaning slides and microscope objectives. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

EM CYTOLOGY or ULTRASTRUCTURE

Using electron micrographs in your textbook, the lab atlases, and a few indicated slides in your boxes, learn to recognize the cell components listed below. The objective is to learn to identify the components of cells, rather than to identify specific cells or tissues as seen with the electron microscope. Understand the functions of each of these structures, and be able to identify them in electron micrographs. Terms which appear in the laboratory directions in BOLD TYPE indicate structures for which students will be held responsible on laboratory exams. (References to figures in the text-atlas are given as Fig. or Plate #s, in Ross et al.'s Atlas 4th ed). Note that structures not in bold are still important for the written exams. Although a few microscope slides are used in this exercise, these can be looked at in your own time. Most of the cytology, as mentioned, is to be done from atlases I. Plasma membrane or plasmalemma Fig 2.2 II. Nucleus A. nuclear membrane (nuclear envelope) (Fig. 2.60, 2.62) B. nuclear pores Fig. 2.60 C. chromatin 1. heterochromatin 2. euchromatin D. nucleolus and its parts (Fig. 2.54, 2.57) To avoid confusion in terminology, try not to call the plasmalemma the 'cell membrane', since 'cell membrane' is sometimes used to refer to other membranes within the cell III. CYTOPLASM A. Organelles 1. mitochondria (Fig. 2.23, 2.35 and Slide A-3) Slide A-3 is a special preparation of liver from an amphibian in which some of the liver cells carry brown pigment. Mitochondria are demonstrated in the non-pigmented cells, in which they appear as tiny blue-black granules in the cytoplasm - very tiny (if you cannot find them, move on). 2. endoplasmic reticulum a. granular (rough (Figs. 2.23, 2.24, 2.28, 11.5) b. agranular (smooth (Fig. 2.29 & Fig 21.7) 3. ribosomes and polysomes (polyribosomes) Fig. 2.12 4. Golgi complex (Golgi apparatus) EM Figs. 2.31, 2.22, 11.5;16.23 In slide A4, the Golgi complex stains black in the cells, and appears as a black squiggly material near the nucleus. (The nucleus does not stain, and in most cases appears as a vacant space in the cell - a negative image) 5. cell center (centrosome) = where the paired centrioles are (Fig. 2.51) 6. lysosomes (Figs. 2.22, 5.17 ) 7. microbodies (peroxisomes) Fig. 17.13 8. microtubules (Figs. 2.37, 2.49, 2.51, 4.6) 9. microfilaments/actin filaments (Figs. 2.42, 2.45, 4.3, 10.6, 10.17) B. INCLUSIONS 1. fat droplets Figs. 20.22, 21.7, & 17.9; & Chapter 6 2. glycogen E-32 The middle inset Fig on the cover of Ross et al.'s book shows glycogen (red) in the liver; then Fig. 2.53; & Plate 62. Fig 2) 3. secretory granules E-6 (Figs. 2.12, 2.31, 17.21) [can later be distinguished from primary lysosomes, if you know that the cell is glandular and hence secretory] 4. pigment granules F-2 Fig 14.8; Plate 39, Figs 2 &. 3 5. mucous precursor droplets/granules see Figs 16.22 & 16.23 Cell Surface Specializations IV. CELL SURFACE SPECIALIZATIONS I. Viewed with light microscope [move the fine focusing as you look] A. specializations of apical surface 1. cilia G-5, G-7 Fig 4.5; Plate 67 Fig 3 2. microvillous border (brush/striated border) (Plate 56, Fig. 3) E-10, E-11, E-12, E-13 3. stereocilia K-7, K-3 (Fig 21.23; Plate 84, Fig. 2) (K3 should be testis & epididymis, but not all slides have epididymis with stereocilia on them) II. Viewed with electron microscope A. specializations of apical surface 1. cilia (Figs. 4.6, 22) 2. flagellum (Sperm's tail) 3. microvillous border of light microscopy (Fig. 4.2c) a. glycocalyx b. microvilli Fig 4.3 [very long microvilli are stereocilia] 4. stereocilia Figs 4.4 & 21.24 B. specializations of lateral surface 1. junctional complex (terminal bar of light microscopy) (Figs. 4.8, 4.7) a. zonula occludens/tight junction (Fig. 4.9) b. zonula adherens (Figs. 4.11, 4.14) c. macula adherens (desmosome) (Fig. 4.13) (1) attachment plaques (2) tonofilaments 2. interdigitations of plasmalemma Fig 4.15, 4.19 3. gap junction (nexus) (Figs. 8.7 & 24.14) 4. desmosomes (Fig. 4.15, 4.16) 5. intercellular canaliculi (Figs. 17.14, ) C. specializations of basal surface 1. basement membrane of light microscopy a. basal lamina: (Figs. 4.19, 4.21, 4.17b) (1) lamina densa (2) lamina lucida b. reticular lamina 2. hemidesmosomes: (Fig. 4.24) 3. basal infoldings(striations): (Figs 4.25, 19.18) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - FIGURES IN SCOPE CYTOLOGY This guide is to help you find electron-microscopic views of various cell structures in the brief blue Scope Cytology book to be found on the side bench in the lab (and TO REMAIN IN THE LAB). But your textbook is the principal source of EM views. Cell Membrane Specializations p. 20, Fig. 4 Junctional complex p. 20, Fig. 5 Microvilli forming a brush border p. 24, Fig. 12 Microvilli (SEM view) p. 64, Figs. 54a, 54b Cilia p. 65, Fig. 55 Cilia (SEM) p. 57, Fig. 48 Desmosome or macula adherens (compare with desmosome at lower magn. p. 20, Fig 5) Organelles p. 32, Fig. 20 Mitochondria p. 31, Figs. 19a, 19b P. 30, Fig. 18 p. 29, Fig. 16 p. 30, Fig. 17 p. 40, Fig. 27 Granular/rough endoplasmic reticulum p. 41, Fig. 28 p. 42, Fig. 29 p. 43, Fig. 31 Smooth/agranular endoplasmic reticulum p. 44, Fig. 32 Sarcoplasmic reticulum Now that you have seen both LM and EM views of cells and tissues, you can read through the following with more understanding of the two viewpoints the techniques offer, and of the limitations on what one can see and do. ----------------------------------------------------------------------------------------------------------------- Some differences between light and electron microscopy LIGHT MICROSCOPY ELECTRON MICROSCOPY - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Section thickness (1-30 micron) gives Very thin sections provide no a little depth of focus for depth of focus, but 3-D information appreciation of the third dimension. can be had from: (a) thicker sections Serial sections can be cut, viewed by high-voltage EM; (b) shadowed and used to build a composite image replicas of fractured surfaces; (c) or representation. scanning electron microscopy (SEM). Most materials and structures cannot Heavy metal staining gives a more be stained and viewed at the same comprehensive picture of membranes, time; stains are used selectively to granules, filaments, crystals, etc.; give a partial picture, e.g., a stain but this view is incomplete and even for mucus counterstained to show visible bodies can be improved by cell nuclei. varying the technique. Specimen can be large and Specimen is in a vacuum. Its small size even alive. creates more problems with sampling and orientation. Image is presented directly to the Image is in shades of green on eye. Image keeps the colors given the screen; photographically, the specimen by staining. only in black and white. Modest magnification to X 1500; High magnification, up to X 2,000,000 but a wider field of view and easier thus the range of magnification orientation is greater Resolving power to 0.25 micron. Resolving power to 1 nm (0.001 mm.) Frozen sections can yield an image Processing of tissue takes a day at within 20 minutes. least Crude techniques of preparation High resolution and magnification introduce many artefacts. demand good fixation (e.g. by (Histochemical methods are better.) vascular perfusion), cleanliness and careful cutting, adding up to fewer artefacts.

HISTOLOGY LAB 2: Epithelial Tissues

In the lab, some of you may be feeling lost in sea of pink. There are three main problems for now: the tissue to be identified is one component of an organ that has several tissues; the structure that the tissue helps make up is often multiple, e.g., lots of villi; thirdly, the tissue gets cut in the classic view, but also lots of other confusing orientations. At least with epithelium, we know where to starting looking - at the free surface of the tissue, having identified the unnatural cut margins from when the organ was cut up small. One page ahead is a section of comments on difficulties with the slides. Life will be easier if, each time, you read though the comments before looking at the slides. The comments try to answer the questions that keep arising. I. Simple epithelia A. simple columnar Figs 3.1b, 4.26, 4.2; Plates 55 & 56 Fig 3 1. intestine E-10 through E-15 (stop once you have a good example) 2. stomach E-5 through E-8 (stop once you have a good example) 3. gallbladder E-33, E-34 4. some ducts of salivary glands E-22 (columnar epithelium may be absent from your slide, so do not spend much time on this example) The simple columnar epithelium of the gut in places shows how the section cut can make the simple epithelium look stratified and composed of cells with round nuclei. Follow the epithelium along until it appears tall and simple. Also, ignore any round very dark lymphocyte nuclei within the epithelium. Now, read fast through the other comments at the end of the section so as to avoid spending time on a problem item. B. simple squamous Plate 1 1. epithelium of Bowman's capsule of kidney H-1, H-2, H-3 Fig. 1.2 2. mesothelium A-5 Plate 1 Fig 2 (face-on view of two simple squamous epithelial membranes arranged back-to-back) 3. endothelium of blood vessels, e.g., heart B-7 Fig 12.20, 12.7b C. simple cuboidal Fig 3.1a 1. kidney tubules H-1, H-2 (Plates 72 & 73) 2. uterine tube for ciliated columnar or cuboidal (no slide) see Fig 22.15b II. Pseudostratified columnar epithelium Plate 2, Fig 18.6 A. respiratory system Figs 4.5, 4.16, 1. trachea G-5, G-6 See Fig 18.6 for low-power TEM B. male reproductive system 1. epididymis K-7 (Fig. 21.23) 2. ductus deferens K-9 Fig 21.25b III. Stratified epithelia Plate 2 A. stratified squamous 1. non-keratinized (cells do not lack keratin intermediate filaments) a. esophagus E-2 Figs 16.2, 16.3; Plate 50 b. vagina L-11 Figs 22.27 & 22.28 c. cervix L-10 Plate 94 (note an abrupt epithelial transition from simple columnar to stratified squamous) B. stratified squamous 2. keratinized Plates 38 & 39 skin F-1, F-2 C. transitional (Fig 19.22; Plates 74, 75) 1. urinary bladder H-6, H-7 Fig 19.22 2. ureter H-4, H-5 D. stratified cuboidal 1. duct of sweat gland F-1, F-2 (Plate 41) E. stratified columnar 1. duct of salivary gland E-21, E-22 (Fig 15.28) (many ducts, maybe in your slides, are lined by simple cuboidal or columnar epithelium) COMMENTS ON EPITHELIAL HISTO. LAB
A Simple squamous epithelium
For now, just classify this as such, regardless of whether a particular example is endothelium, mesothelium, or epithelium

1 Problems of finding it in the H-1 kidney slide are: (i) that this thin plastic section has the corpuscles widely spaced (because it is thin) and the stain is weak, so that there is little contrast between the corpuscles and the surrounding tubules; (ii) the corpuscle is dominated by the irregular, tangled glomerulus, which may reach right out to touch the capsule, therefore finding the epithelium of the enclosing capsule takes perseverance.

2 Slide A-5 of silver-stained mesentery outlining mesothelial cells has a lot of gold or brown precipitate (junk) to confuse the picture. Also, the cell outlines are often incompletely stained, and the two epithelial layers are at different depths of focus.

3 The heart (B-7) is itself a vessel lined by endothelium. However, its inner surface is irregular and extends in as valves. Any simple squamous epithelium will appear only as a thin line of flat, dark nuclei at a free surface with occasional hints of cytoplasm, if the epithelium has stayed intact. The small vessels at the heart's outer surface present another problem: most are cut in cross- section, and because the lining endothelial cells run lengthwise with the vessel, their nuclei appear only as dots at the inner margin.

B Stratified squamous epithelium, non-keratinized
Where the uterine cervix protrudes some way into the vagina (L-10), the epithelium is mostly the protective stratified squamous (non-cornified) variety. Hunting far and wide along this epithelium should eventually reveal a region of simple columnar ep. well inside the uterus. (There may be stretches of stratified columnar ep., as well.) The picture here and in many other organs is visually complicated because tubular glands, also lined by simple columnar epithelium, extend down from the surface epithelium, with which we are primarily concerned. This situation arises in the stomach (E-5) and colon, where there is not that much surface epithelium, but most of the epithelial tissue is actually glandular below the surface lining the organ. The glandular epithelium is less clearly a simple columnar ep. since the epithelium is forced into the tubular shape of the little gland.

C Pseudostratified columnar epithelia
The airway epithelium has several cell types, and an apparent multilayering based on the nuclei, whereas the epithelium of the ductus deferens and epididymis has two layers of nuclei and only two cell types - tall columnar and short basal. Both sites have features that suggest the location in the body (pale mucus-secreting goblet cells and cilia - airway lining; sperm in the male lumen), and from seeing these features one can infer indirectly that the situation is 'pseudo' rather than truly stratified. Slide G-9 of lung has little if any sign of bronchi: it was cut too peripheral to the main airway. Slide G-6 of trachea has a ragged epithelium, heavily infiltrated with lymphocytes - the small, dark nuclei, but the BM shows up as a pale gray band just below the epithelium. A general problem with epithelia at first is to see the epithelial cells, but to ignore the many connective tissue cells of the underlying lamina propria. In places the pseudostratified columnar epithelium of the airway undergoes metaplasia (conversion) into a more stratified squamous epithelium. This you may encounter as scattered islands of abnormality in the epithelium.
In the testis slide, do not confuse the tails of maturing sperm sticking out into the lumen of the tubules in the testis itself with the stereocilia of the nearby epididymal epithelium. (Stereocilia are inappropriately named long microvilli, with no microtubules and no ability to beat.)

D Cilia and microvilli
In LM, cilia should be long and spiky, and individually distinct as you use the fine focusing. Microvilli, when densely packed as a brush/striated border, are about one third the height of cilia, are not seen individually, and stain PAS+. Brush borders, terminal bars, prickle cells etc. need oil immersion objectives and good specimens to be seen convincingly.

E Keratinized stratified squamous epithelium
The keratin tends to break up into tatty layers, when processed and cut for LM histology. In 'thick skin' (F-1) note that roughly half the thickness of the epithelium is living cellular tissue (next to the connective-tissue dermis), whereas the outer half is a dead, but still cellular keratin layer. You need now only know the epithelial type, not thick-thin differences, nor the several layers in the epithelium except for the keratin and living layers.

F Stratified cuboidal epithelium
This epithelium is recognized from the two concentric rings of round nuclei. The sweat gland ducts are small, dark structures, mostly far down in the dermis away from the surface epithelium of the skin. Some regions of the duct system in salivary glands have strat. cuboid ep. However, along the total length of the system, simple and stratified cuboidal and columnar epithelia, and transition forms, can be seen, depending on the luck of the section. Go by the rule - that at a particular site what is there is what is there - and start to rely on your own judgment.

G Transitional epithelium (Urothelium)
The plastic-imbedded bladder slide (H-7) has some dark cells flattened on the surface of the epithelium. These do not look like typical surface umbrella cells, but may be dead or dying cells, cast of from the bladder or upstream in the urinary system that have stuck to the surface.


HUMAN STRUCTURE HISTOLOGY LAB 3: Neural Tissue

Neural/nervous tissues are treated here, and again at the end of Human Structure, so as to be close to the Neurobiology Module. If you like, skip items VIII though X: We'll come to them in due course. I. Neurons/nerve cells A. pseudounipolar neurons (Fig. 11.2; Plate 23) 1. spinal (dorsal root) ganglion cells C-2 Before searching for the ganglion cells, examine the slide with the naked eye to make sure that there is a DR ganglion present, in addition to the spinal cord B. multipolar neurons 1. Purkinje cells of cerebellum C-9, C-10 (Plate 26 Fig 2) 2. ventral horn motor neurons of spinal cord C-1, C-2, C-3 (Fig 11.4; Plate 27 Fig 2) 3. Nissl bodies are clumped granular ER Be able to ID in TEM - see Fig 11.5 II. Nerve fibers Plate 24 A. myelinated nerve fibers C-4, C-5, C-6 (Figs 11.13, 11.10, 11.24; Plate 40) 1. myelin sheath C-4 2. nodes of Ranvier C-5 Fig 11.10b 3. Schwann cells Figs 11.12, 11.16 B. non-myelinated nerve fibers K-11 (Fig. 11.14, 11.19) III. Spinal cord C-1, C-2, C-3 (Fig 11.26; Plate 27; Fig 11.23) A. white matter B. gray matter C. dorsal and ventral horns IV. Ganglia Plate 23 A. sensory ganglia: an example is the spinal/dorsal root ganglion C-2 (Fig 11.17) Find satellite cells around the neuron bodies B. autonomic/motor ganglia 1. sympathetic C-14 (Plate 23 Figs 1 & 27) 2. parasympathetic K-11, E-14 Plate 53 Fig 2; Fig 16.28 AUTONOMIC GANGLION presents an unbalanced ID. One can be sure of a parasympathetic ganglion, if one sees a few (indeed, one) neuron bodies amongst the smooth muscle of a visceral organ's wall. However, to ID a sympathetic ganglion requires high power to recognize the neurons and low power to see that the ganglion is quite large, has its own capsule, and is not part of any other organ. Hence, we will take "autonomic gangion" for parasymp & symp. V Peripheral nerves (Fig 11.10; Plate 21; Plate 24) C-2, C-4, C-6, K-10, K-11, K-12 A. classification 1. myelinated 2. unmyelinated (a classification needing EM for certainty) Fig 18.21 3. mixed B. Nerve connective tissue coverings 1. endoneurium, recognizable as collagen fibrils in TEM 2. perineurium 3. epineurium (may include large fat cells - black with OsO4) 2. C. Nerve TEM detail Fig 11.13 1. Axon 2. Myelin lamellae 3. Internal & external mesaxons 4. Schwann cells Fig 11.12 5. Synapses Fig 11.9, 11.17, 10.9 VI. Synapses: identify in TEM, & as boutons termineaux C-3, C-14 (Figs 11.5 & 11.7) SYNAPSES C-3 spinal cord. The silver stain shows white-matter axons around the central grey matter where the ventral-horn neurons are yellowish-brown. On the yellow body and start of the dendrites are tiny black structures that sometimes appear as rings with tails. This is as exciting as synapses get. You will encounter their old name "boutons terminaux" from Cajal's publications in French. VII. Motor end-plate in TEM Fig.10.9 1. Prejunctional (axonal) membrane 2. Postjunctional (sarcolemmal) membrane (folded) 3. Vesicles 4. Synaptic Cleft VIII. Sensory receptors [If you are short on time (and you will have to hunt all along the skin sections), look at the atlas Figs and save the slide searching for when we do skin.] (Fig. 14.13; Plate 42) A. Paccinian corpuscle: skin F-4 B. Meissner's corpuscle: skin F-4 XI. Cerebellum Fig. 11.23. Plate 26 1. Purkinje cells 2. Granular layer 3. Molecular layer 4. White matter 5. Folia with pial covering X. Cerebral cortex (cerebrum) Plate 25 1. Pial surface 2. Gray matter of gyrus 3. White matter with oligodendrocyte nuclei 4. Deep gray-matter (layer V has the largest pyramidal neurons see Fig 11.29 and Plate 25 Fig 5, where "Pyramidal cells (PC) are readily recognized", or so is Ross et al.'s questionable claim) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - . FORMAT OF LAB EXAM QUESTIONS IN HISTOLOGY with nervous-system examples By each microscope or electron micrograph will be a card with a number(s) and question(s). How do you know to what the question on the card refers? Assume the object is at the tip of the eyepiece pointer. However, the card may specify: at the pointer; around the pointer; filling the field (of view); filling most of the field; or at the orange arrow (on an electron micrograph). If in doubt about the question, put up your hand, and we shall hold the clock while the problem is being resolved. [Yes. Stations are limited to around 1.25 minutes each.] Question Sample answer Location 1 Name the tissue Simple columnar epithelium Spinal ependyma Fairly dense irregular C.T. Epineurium 2 The structure? Mesaxon; perineurium; Meissner's corpuscle; synaptic vesicles; etc. 3 Name the structure filling most of the field Nerve (myelinated) Node of Ranvier Node in TEM Motor end-plate Endplate in TEM 4 Name the organ Autonomic ganglion; cerebellum* 5 The material? Myelin; Mainly RNA Nucleolus 6 What process is Myelination; occurring? Wallerian degeneration; CSF production Choroid plexus 7 What is the cell? Purkinje cell; satellite cell; Spinal ventral-horn motoneuron; Schwann cell; etc. The lesson is that one should read carefully the question(s) on each card and answer precisely what is asked. *For histology, parts of the brain and organs-within-organs, such as blood vessels, parasympathetic ganglia, nerves, and lymph nodes, count as organs. Question #1 on tissues is more useful for epithelia and connective tissue than for nervous tissue. TIPS 1 Remembering the identifying features of the cell, tissue, etc., keep checking against this list after you have provisionally identified the item, i.e., something has sprung rapidly to mind. 2 Note the special appearance of preparations stained for such structures as myelin sheaths, mast cell granules, synaptic rings, and elastic fibers. 3 Give as full an answer as possible, e.g., autonomic ganglion (parasym.) 4 While reviewing, also go down from high power to see how things you know appear at one power down. The exam may use a lower power to show more context for a structure.

At the start of the Histology Lab exam you will be given the directions listed below. . Please read these over before coming to the exam, to smooth the start.

HISTO LAB EXAM DIRECTIONS

Outside - come on in, pick up an answer sheet on the nearest bench, find a seat anywhere (including the rest stop). Do NOT start, but read the directions on the chalkboard.

Everyone seated, make sure that all places are filled. . If not, hunt down more bodies from Gross.

Everyone here, show the benches for Free-range, where all controls should be used, but the ‘scope left on low power, with something useful in the field, when you move

Spots are stations 21 through 50, and mean using ONLY the fine focus (which should always be used). . Not even the eyepiece spacing should be changed. . If in doubt, you should use the ‘scope as a monocular, looking down the eyepiece with the pointer. . Some EM Figs (TEM & SEM) are amongst the Spots

The direction of movement, at the bell, is on the board - basically to your right, with spilling down to the next bench closer to the door.

Time per station is 1 1/4 minutes - more than enough for most Spots, but needed for the Free-range.

On the bench by the door, the last station ( # 50) leads next to the extra-credit item on the high bench nearby. . From there, one walks the length of the room to the Rest Stop by station #1

Do not put your feet on the bench; and baseball caps should be turned bill backwards: both so as not to jar the ‘scope

If you know, or think, that you have banged the ‘scope, put up your hand and we will check it.

If the question on the card does not match what the pointer is on in the field, again, put up your hand.

Put complete answers, e.g., kerat strat squam ep, but abbreviate

Put only one clear answer, but do not leave blank spaces - guess

Answer the question on the card - Organ? Tissue? Cell? Structure? Material? Activity/Process?

Only one person - at station # 1 - puts his or her first answer in the # 1 place on the answer sheet, where the numbers go with those on the question cards

Any questions? If not, Start


HISTOLOGY LAB 4: Connective Tissues

The study of connective tissue is divided into two parts: (1) the various components of connective tissue, and (2) organization of these components into tissues referred to as connective tissues. I. Connective tissue components A. CELLS 1. fibroblasts E-10, H-6 Fig 5.14; Plate 5 2. macrophages G-9, G-10 Figs 18.20, 18.21 & 5.17 3. plasma cells E-15 Plate 48 Fig 2; Plate 63 Figs 3 & 2; EM Fig 5.21; Plate 49 Fig 3 is poor & too red 4. mast cells A-9 Figs 5.1 & 5.18 5. adipose/fat cells A-9, C-4, F-1, M-14 Fig 6.2 6. mesenchymal cells, around developing tooth M-9, M-10 (Fig 5.2, Fig 15.10 g,h) The mesenchyme, with mesenchymal cells, is only the very pale tissue right around the tooth germ and in a few other places between already several differentiating tissues. Macrophages here can be reliably identified only after they have phagocytosed particles that remain partly undigested and visible, e.g., dust, grit, trypan dyes. [Macrophages can be found in clinical labs by immunostaining special glycoproteins on their surface.] The spread (A-9) Fig 5.1 varies greatly in thickness, so that a lot of structures can be seen in some regions; elsewhere, at the edges it may thin out to something like a section's thickness. The technique triggers de-granulation in some of the mast cells. It also results in a few globs of stain in places. These are artifact, not cells! The two stains show quite a lot, so that a third stain in not needed. In E-15 of GI tract it is difficult to find plasma cells for various reasons - there is too much red eosin, so that the cells are not as blue as they should be; the section is thick, so that the cells are piled up close and are often not to be seen as separate entities. The ID of fibroblasts is 'guilt by association'. If there is a solitary elongated cell attached to a collagen fiber in a dense connective tissue, it is probably a fibroblast. In loose CT, where there are more defensive cells (a looser, more favorable home for microorganisms), the odds are less in favor of the fibroblast. B. FIBERS 1. collagen fibers A-9, F-3, F-4 Fig 5.4 & 5.10, Plate 5 2. reticular fibers D-6 Figs 5.9 & 13.19 3. elastic fibers A-9, B-1, B-2, B-3 Figs 5.10 & 12.7a; Plate 6; Plate 39 Fig 3 4. elastic membranes/laminae Fig 12.7 (appreciate that elastic layers look like fibers when seen edge-on) II. CONNECTIVE TISSUES A. dense fibrous connective tissue 1. dense regular connective tissue a. with collagen fibers A-6 (Plate 9) b. with elastic fibers (no slide) 2. dense irregular connective tissue a. with collagen fibers F-1, F-3, F-4 (Figs. 14.1, 14.2, 22.33) b. with elastic fibers B-3 (Plate 10) B. adipose tissue C-4, F-4, M-14 (Figs. in Chapter 6) Slide M-14 has excellent examples of adipose tissue stained with silver and demonstrating the reticular fiber supporting the individual adipose cells. C. loose fibrous connective tissue (areolar) A-8, A-9, A-10, E-5, E-10 (Plate 10) [Many sites of loose areolar tissue, e.g., in the G-I tract and airway, beome so infiltrated with defensive cells such as lymphocytes, plasma cells, and macrophages that their connective-tissue character becomes obscured Fig 16.16; Plates 55 & 58 Fig 2.] D. mesenchyme (mesenchymal connective tissue) M-9 (Fig. 5.2) E. mucoid connective tissue: umbilical cord L-16 Fig 5.2b In umbilical cord (slide L-16), the mucoid connective tissue looks like a slightly denser textured version of mesenchyme, which is what it is. It can only be identified with confidence under low power, when the three umbilical blood vessels can be seen to give the pale tissue a recognizable context. Some FIBRIL assemblies to be kept separate in one's mind: pro-collagen --> collagen --> collagen fibrils --> collagen fibers fibrillin --> fibrillin fibrils [stay fine to influence elastin orientation] fibrinogen --> fibrin fibrils (temporary, to reinforce a blood clot)

HISTOLOGY LAB 5: Muscle

I. Muscle tissue studied by light microscopy A-22, with three kinds of muscle, unwisely includes uterus for the smooth muscle. Here, there is little connective tissue for comparison, and the muscle runs every which way so that good transverse and longitudinal views are the exception. Obliquely cut smooth muscle is confusing for the novice. A. skeletal muscle A-22, A-23 (Fig 10.1; Plate 18) 1. examined in cross-section a. fibers b. myofibrils c. connective tissue (1) endomysium (2) perimysium Plate 18 Fig 2; Fig 10.11b (3) epimysium (we don't have a good example) 2. examined in longitudinal section to show the cross-banded or striated nature of the muscle. a. fibers b. myofibrils c. sarcomeres (1) A-band (2) I-band (3) Z-line (needs oil immersion & good staining) In the trichrome-stained skeletal muscle (A-23), some of the muscle fibers/cells have degenerated into pale blue forms, but still holding much of their original shape and size. Epimysium is absent, but thick amounts of greeen connective tissue will be perimysium. The endomysium can just be made out as thin green lines in places between the muscle fibers. Developing skeletal muscle fibers can be seen as they attach to the periosteum of developing bomes in slides A-16, A-18, & A-21. Other embryonic slides are likely to have developing muscle. B. cardiac muscle A-22, B-6, B-7, B-8 (Fig 10.13; Plate 20) 1. examined in cross section. Under low power first establish the cut margins of the heart specimen, and whether you have both pericardium (fatty with blood vessels and/or the endocardium - can be very thin indeed) a. fibers 2. examined in longitudinal section a. fibers b. intercalated disks c. sarcomeres 3. Purkinje fibers B-8 Fig 12.21 & Plate 21 (subendocardial in location, larger and paler than the usual cardiac myofibers. There are a surprising number of them. A confusing aspect is the irregular nature of the lining to the ventricle - many folds are caught in cross-section. C. smooth muscle E-1 through E-17 (E-16 is v good) Plate 22; Fig 10.16 1. examined in cross section a. fibers 2. examined in longitudinal section a. fibers b. comparison with other muscle types (Plate 50 Fig 1 inset) II. Muscle tissue studied by electron microscopy Figs 10.4, 10.6, 10.15, 10.17, 10.18 A. skeletal muscle 1. myofibrils & thick & thin myofilaments 2. sarcomeres a. A band b. I band c. H zone d. M band e. Z line 3. Neuromuscular junction Fig 10.9 3. triad a. sarcoplasmic reticulum b. transverse/T tubule B. cardiac muscle (Plate 32) 1. myofilaments 2. intercalated disc a. macula adherens b. fascia adherens c. gap junctions C. smooth muscle (Figs. 10.14, 10.15) Just a reminder that to see things like cross-striations, one needs to cut down the glare with the condenser diaphragm (lever under the stage) and to use the fine focusing while observing. B-7 Heart: one can just about see striations on cardiac muscle, but the Z-lines are hardly to be seen - sometimes a staggered line across the fiber. B-8 Heart for Purkinje fibers Fig 12.21. Scan across this slide under low power to find the relatively smooth epicardium, and the very folded inside (endocardium) of the heart. The Purkinje fiber are in the sub-endocardium next to the wide dark myocardium with which the fibers can occasionally be seen to merge. Although fat-like under low power, the Purkinje fibers have a little cytoskeleton left that holds the nucleus centrally (not a mark of fat cells). B-7 is a complicated slide with ventricular wall changing to cardiac skeleton (Conn Tiss), then going on to become elastic artery. It is from the pale "skeletal" CT that the thin floppy semilunar valve extends.

HISTOLOGY LAB 7: Cartilage

While studying cartilage in its various forms, keep in mind that cartilage is a specialized connective tissue and has many characteristics in common with the connective tissues already studied. I. Types of cartilage A. hyaline cartilage Plate 7 & Plate 8 Fig 2 1. cells are called chondrocytes G-5, G-6, G-7 2. matrix: same slides and figures a. lacunae (holes for chondrocytes) b differences in proteoglycan content may show up as a darker territorial matrix around the cell and a paler inter-territorial matrix further away 3. perichondrium G-5, G-6, G-7 Fig 7.2 B. elastic cartilage A-11, A-12 Fig 7.8 & Plate 9 note cells, matrix (including fibers) and perichondrium [The elastic fibers stain weakly with eosin. All one can truthfully say with H&E is that the matrix does not look basophilic enough for hyaline cartilage. It takes an elastic stain to confirm the cartilage as elastic.] C. fibrocartilage A-13, A-14 Plate 10 & Fig 7.9 Note round or ovoid cells within lacunae, fibrous matrix (with visible collagen fibers) and lack of a perichondrium II.Chondrogenesis: using the same slides, note how elastic and hyaline cartilage have two, spatially separated cell populations for growth: appositional from proliferating cells at the inner perichondrium, and interstitial, by continued internal synthesis of matrix, and reflected in the groups of chondrocytes in the interior. Fig 7.3 Slide G-9 (most of them) is too peripheral in the lung for the bronchi (with cartilage) not to have turned into bronchioles without cartilage. Thus, this slide has no cartilage! A-12 Elastic cartilage should have a blue-black appearance from the elastic fibers in the matrix. However, in an HE-stained section all one can say about elastic cartilage is that the perichondrium, and shape, pairing and spacing of the chondrocytes look OK for hyaline cartilage, but the matrix looks wrong in that it is a bit pink and fuzzy. The intervertebral disk slide for fibrocartilage is confusing because there are three tissues present, and two quite wide transition zones between them. On the outside is dense irregular CT; deeper, is fibrocartilage with paired chondrocytes in layers of dense collagen running in at least two different directions. In the core of the disk is the nucleus pulposus - a unique non-cartilaginous scruffy- looking tissue. Thus, there is another zone of merging between this and the annulus fibrosus of fibrocartilage. A-6 is supposed to have some fibrocartilage, but in most cases has only flat squitty fibroblasts amongst the collagen fibers. Occasionally you may see fatter, rounded cells with a fine dark lacunar wall, worth calling chondrocytes that would make that small area one of fibrocartilage. The shift from dense regular tendinous CT to fibrocartilage normally takes place right at the insertion into the bone which we don't have here.

HISTOLOGY LAB 8: Bone and Osteogenesis

Again, read the comments at the end first! They will help. I. Histology of adult bone A. macroscopic anatomy (demonstration) (Figs. 8.1, 8.2) 1. compact bone 2. cancellous (spongy) bone B. bone in dry ground specimens A-15 Plate 11 1. osteons (Haversian systems) a. Haversian lamellae b. Haversian canal c. lacuna d. canaliculi 2. Volkmann's canals 3. circumferential lamellae (not likely to be visible on most specimens unless the section includes a complete cross-section through a long bone) a. outer b. inner 4. interstitial lamellae (between osteons) C. bone in demineralized specimens A-16 through A-21 Plate 12; Figs 8.6 & 8.8 1. periosteum (Plate 18) a. outer fibrous layer b. inner cellular (osteogenic) layer c. Sharpey's fibers (fibers of attachment) M-14, M-17 2. endosteum A-16, A-18 3. cells (Figs. 8.6 - 8.9) a. osteoblasts A-14 & A-16 through A-21, M-16 b. osteocytes A-14 & A-16 through A-21 c. osteoclasts A-14 & M-16 4. remodeling effects M-14, M-16 (Fig. 8.17) a. depository surfaces (smooth) b. resorptive surfaces (rough & eroded) Bone matrix in a well-balanced H & E prep. should stain red from the densely packed collagen fibrils. If the eosin is weak, the matrix end up blueish. Canaliculi do not show up with H & E. II. Histology of developing bone A. intramembranous osteogenesis: A-19, M-9, M-10 Plate 15 & Fig 8.13 (Look for bone of tooth socket in these embryonic faces.) 1. bone trabeculae a. cells (1) osteoblasts (2) osteocytes (3) osteoclasts b. extracellular bone matrix 2. periosteum a. outer fibrous layer b. inner cellular layer 3. endosteum B. endochondral osteogenesis: A-14, A-16, A-17, A-18, A-20, A-21 Plates 13 & 14 Figs. 8.16 & 8.20 1. hyaline cartilage model 2. periosteal bony collar 3. vascular invasion - periosteal bud 4. stages (seen as zones/layers) in replacement of cartilage a. chondrocyte proliferation b. chondrocyte hypertrophy c. calcification of cartilage matrix d. selective resorption of calcified matrix by chondroclasts, etc e. deposition of bone f. selective resorption of newly-deposited bone 5. primary and secondary centers of ossification 6. epiphyseal plate A-18 (all), A-16 (some) Secondary centers of ossification are rare in our specimens, but in some A-21 slides the earliest signs of secondary osteogenesis can be seen in the epiphyseal ends of these bones. There is no growth plate until the 2nd center is established. 7. Distinction between intramembranous and endochondral bone (endochondral bone has residual islands of blueish cartilage matrix left in the bone matrix Fig 8.15) III. Histology of synovial joints: for developing joints A-20, A-17 (small and all tissues are immature, making distinctions difficult - see Fig 7.5) A. joint capsule B. articular cartilage C. synovial membrane 1. macrophage-like cells (not to be distinguished in H&E) 2. fibroblast-like cells D. joint space/cavity On the bone slides, marrow, with its many forming blood cells and/or fat cells, is a confusing factor that has to be visually subtracted from what belongs to bone, namely the very thin endosteum covering all internal surfaces. The cells covering and lining bone often get lifted off as an artefact. This artifactual separation is common with osteoclasts, which seem to hover above the resorption lacuna. Beware the two lacunae of bone - the open pit under osteoclasts, and the enclosing lacuna inside the matrix for the osteocyte body One result of osteoclasts eating into bone is to leave projecting spurs, which may acquire an osteoclast cap to bring down the protrusion. A problem with some of our bone slides is that the H & E balance is wrong and favors hematoxylin so that bone matrix looks blueish (and a bit cartilage-like) instead of red from the abundant collagen fibrils. Periosteum is best identified under low power, where you can see the domain of the bone occupied by trabeculae, and an outer limiting connective tissue, maybe pale and undeveloped around the perimeter. A-17 is plastic slide of fetal finger. There are a lot of tissues present - forming skin with glands, developing tendon, along with a developing bone, still mostly cartilage. The actual bone forms a very pale gray collar around the middle of the cartilage. Cells against the gray on the outside are cellular periosteum. Outside these is a longitudinally oriented layer of cells (fibroblasts) that will later form the fibrous periosteum. In these young bones, the mechanical stresses to get a dense irregular fibrous outer layer to the periosteum have not yet acted. The periosteum needs to be identified under low or medium power where perimeter or the outer limit to the bone formation site can be identified. In these young bones, the inner cellular layer of the periosteum is the only component established. A-15 of ground bone in some sets has black cracks running through it. Borrow a better specimen. Look to see if yours has any natural margins, i.e. outer and inner surfaces, or is cut out of the dense bone as a block with four cut surfaces. The idea is that if periosteal or endosteal surfaces are present you might see a Volkmann's canal entering. The Haversian canals may be black (air inside) or yellowish from grinding debris. For the lacunae and canaliculi think bugs with a body and legs. For the growth plate or the epiphysis before the secondary ossification center has got going, the layering of zones, e.g. hypertrophy, is best seen at medium power. Do not be surprised if the growth plate wiggles up and down. M-15 of mandible is confusing because it has bone and multiple tooth roots stained gray. The CT periodontal ligaments are brown and from them in some places dark brown lines extend into the gray bone as Sharpey's fibers. A-18 is rather thick and poorly stained, so that the bone trabeculae do appear orange but the cells immediately against them are piled up and hard to recognize. In any spongy bone the endosteum is the cellular layer right against the bone. It is only one cell wide. The rest of the tissue between trabeculae is bone marrow and has no direct relation with the bone. The endosteum at any one site can consist of active osteoblasts, flat resting cells, or sometimes osteoclasts.

HISTOLOGY LAB 9: Skin

I. Epidermis A. thick skin (hairless) vs. thin skin (hairy) F-1, F-2, F-3 (Figs 14.1, 14.2; 14.14; Plates 38 & 39) B. layers F-4 best? 1. stratum basale 2. stratum spinosum Fig 14.3 3. stratum granulosum 4. stratum lucidum (thick skin only, & not necessarily present) 5. stratum corneum II. Dermis F-1, F-2, F-3, F-4 Figs 14.1 & 14.2; Plates 39 Fig 3; 38 Fig 2 A. papillary layer B. reticular layer (no exact demarcation between them) III. Hypodermis F-1, F-2, F-3, F-4 Fig 14.14b (If you see fat cells, you are in hypodermis) IV. APPENDAGES of the skin A. hair F-3 (Figs. 14.13, Plate 43 ) 1. shaft 2. root sheath 3. hair follicle/root (Plate 63.1) (with matrix) 4. dermal papilla 5. arrector pili muscle [Often difficult to recognize because it is cut in cross or oblique section] B. GLANDS Plates 40 & 41 1. sebaceous glands F-3, F-6 2. sweat glands Fig 14.16 a. eccrine sweat glands F-1, F-2, F-3 Fig 14.16 b. apocrine sweat glands (No slide) see Fig 14.18; Plate 40 C. NAILS F-5 (Fig 14.19; Plate 43 Fig 2) V. SENSORY ORGANS of the skin (Figs. 14.13; Plate 42) A. Meissner's corpuscles F-1 (be prepared to hunt along the dermal papillae) B. Pacinian corpuscles F-4 9 (very large and pale) F-3 SKIN Take care on the RETICULAR LAYER. One might think that it was the layer with more delicate fibers. Wrong. The lighter-textured area is the narrow papillary layer just below the epidermis. The Reticular layer is most of the thickness of the dermis where the collagen fibers are thicker.

HISTOLOGY LAB 10: Circulatory System

I. General structure of blood vessels (Fig 12.6, p. 310); this is most clear in medium-sized muscular arteries (and with TEM). The subendothelial connective tissue and adventitial lymphatics are hard to find even with TEM; and elastin needs special staining. A. tunica intima 1. endothelium 2. basal lamina 3. subendothelial connective tissue 4. internal elastic membrane B. tunica media 5. smooth muscle 6. elastic fibers, if stained for C. tunica adventitia (Adventitia being on the outside can be partially torn off - artefact!) 7. external elastic membrane 8. connective tissue 9. vasa vasorum (vessels of vessel) 10. lymphatic vessels II. ARTERIES & ARTERIOLES A. arterioles When does it stop being a small artery and become an arteriole. The old convention was that around five layers of smooth muscle cells was the cut-off! Ross et al.'s book fudges p. 329. Two cells thick is an arteriole; 8 cells thick and above makes it an artery, so what about 3 through 7 layers of smooth muscle? (See their Plate 34 Fig 3 for how they use their terms) Do not worry about this as a lab distinction: we shall grade small artery and arteriole both as correct) B-1 and B-3, in adventitia of a large vessel (Plate 48; Plates 38, 75.2, 31.3, Plate 87; Fig 17.12, 18.4. [A great number of text figures with vessels are listed in this section. Most of these can be studied outside the formal lab time. Here, use only what keeps you moving.] B. muscular arteries B-9, B-3 (in adventitia), L-3 (Plates 47, 34.3; Figs 3.4, 21.25) Plate 22 Fig 3 shows the effect of cutting an artery as it turns, so that some smooth muscle cells are cut in cross-section, others longitudinally 1. tunica intima 2. tunica media 3. tunica adventitia Slide L-3 is a dog ovary, the medulla of which is loaded with muscular arteries and a few muscle-less veins. C. elastic arteries B-1, B-2, B-3 (Plate 46; Fig. 12.3) 1. tunica intima 2. tunica media 3. tunica adventitia a. vasa vasorum b. lymphatic vessels III. VEINS A. venules B-1 and B-3, in adventitia (Plate 7, 6.1(b), 36; Fig 17.20a shows a good venule, [despite the label on the Fig below, it is too wide to be a capillary]) B. veins B-9, B-3 (in adventitia), L-3 (Plate 47; Fig 12.11; Plate 25. Fig 1; Fig 21.25; Plates 83, 87, 88) 1. tunica intima often has valves, but these may be missed even in longitudinal sections C. large veins B-4, B-5 Fig 20.16 1. tunica intima 2. tunica media 3. tunica adventitia a. smooth muscle b. vasa vasorum IV. CAPILLARIES (Find the capillaries in Plate 31.4) endothelium (Figs 19.12, 18.15, 18.19) Recognize in TEM A. with the light microscope B-1, B-3, note the very small size of capillaries. Nerve makes a good background against which to detect capillaries: see Plate 24 Fig 2 Also connective tissue almost anywhere (Figs 9.2, 5.10, 3.2; Plate 20 Fig 4 1. endothelium, (Figs 19.12, 18.15, 18.19 ) B. with the electron microscope 3. continuous capillary ( Plate 69 Fig 4; Plate 65 Fig 2) 2. fenestrated capillary (Fig 12.9, 20.6; Plate 103) [Capillaries are also in Figs 20.23 -- Plates 5.2, 7, 6.1(b), 17, 27.3, 31.4, Plates 40.2, 42.2, 71.2] V. HEART B-6, B-7, B-8 (Plate 45) A. endocardium 1. inner layer a. endothelium b. subendothelial layer (sometimes with smooth muscle) 2. outer, subendocardial layer, only present at certain sites 3. Purkinje fibers B-8 in subendocardium B. myocardium 1. cardiac muscle 2. small amount of connective tissue C. epicardium 1. mesothelium (may have been rubbed off) 2. connective tissue, often with fat 3. blood vessels (coronary vessels) and nerves VI. Lymphatic vessels: around lymph nodes D-4 (Figs 16.12 p. 455, 18.4; Plate 34 Fig 3) Note 1. lack of RBCs, presence of lymphocytes 2. valves We do not have a good slide of the lymphatic capillary lying centrally in intestinal villi, which is termed a lacteal from the white fatty chyle that the gut lymphatics collect, but see Fig 19.19 for one that has stayed wide open Circulatory lab. problems, or why is this lab a pain?
1 With large, small and medium, there are too many terms to choose from. After the experience of having looked at a lot of vessels, the wide range of terms for size is useful, but at first it isn't. For the lab exam, know: elastic artery, muscular artery, arteriole, capillary, vein, large vein/vena cava, and have a try at venule for structures like capillaries but several diameters wider. Think very small for capillaries in LM.

2 The classification of layers/tunics gets pushed beyond good sense. Theory intrudes on the light- microscopic lab. reality. Thus, much of the heart is lined by a very thin endocardium which it is not convincing to subdivide; likewise the intima of an arteriole is negligible in LM. Also the layers can vary in thickness, e.g., the endocardium; or be mixed up as far as the cells are concerned, as in the vena cava where fibroblasts and VSMCs do not respect the others' territory, and produce three tunics with combinations of c.t. and muscle. You should be able to cope with pointer questions on the layering in elastic and muscular arteries, and the heart.

3 Vessels within a class vary quite a bit. The veins within organs, e.g., the heart and ovary, can get quite large without acquiring smooth muscle, whereas small veins in the limbs already have a little muscle in a media. If in doubt about a vessel, cruise around to compare veins and arteries in the same region.

4 Lymphatics are a distraction, but can usually be disregarded because they squash flat. They should have large lumens, very thin walls, valves, but no RBCs. Leave until lymph node, where there have to be lymph vessels going to and from the node (cut them off at the pass!)

5 In large vessels one sees more detail than is comfortable, if the theory has been kept simple. In the outer media of the aorta there are some muscle bundles that run 'longitudinally' (actually in a spiral with a long pitch); in the intima of the vena cava, an internal elastic lamina can be seen; etc.

6 The comparison slide of vein with muscular artery (we don't speak of muscular veins) is stained red for elastic so that the inner line of the artery is the lamina elastica interna. There is more elastic at the start of the adventitia , giving a reasonable impression of an external elastic layer. Between the two is the media in which a few elastic fibers can be seen. As in most vessels of this size, the intima is negligible in light microscopy, leaving only a media and adventitia to be distinguished.

7 For the venule-vein distinction, use for guidance any accompanying artery or arteriole, allowing for the vein or venule to have 2X or 3X wider lumen. On the exam you will be given guidance, e.g., by asking for a one-word answer, that we are not asking for small-medium-large distinctions.

8 In the VASA VASORUM vessels in the adventitia of the aorta, the veins and venules have quite a lot of elastic in them. A guide to both is that any muscle does not form a continuous layer, which it should for arteriole.

9 In the OVARY, there are many arteries and arterioles. The veins are flattened, may have blood cells in them, but are to be distinguished by the endothelial cell nuclei lined up, lining a space in the connective tissue. They need work to be found.

10 CAPILLARIES are very small, so think an order of magnitude down. For cross-sections expect a red RBC around which curves a fine line including one, maybe two, curved endothelial cell nuclei. That's as exciting as it gets.

11 The ADVENTITIA of any tube will blend off into the CT of surrounding structures. Under medium power, one can usually get an idea of where to stop calling the CT adventitia. The same problem arises for periosteum and endosteum.

 


HISTOLOGY LAB 11: Respiratory System

I. Larynx G-4 (Fig. 18.4; Plate 66) A. general structure. Determine the orientation and general structure of the larynx by examining the slide with the naked eye prior to examining it microscopically. Identify the following structures using the naked eye or an objective reversed and used as a magnifying glass. 1. thyroid, cricoid & any tracheal ring cartilages (may have been cut away) 2. vocal fold/cord and the vocalis muscle 3. vestibular fold 4. ventricle B. mucosa 1. Note different epithelial types lining the laryngeal cavity; particularly with respect to the epithelium covering the ventricular and vocal folds. 2. Note position of glands in the larynx. Do not be surprised to find stratified squamous epithelium and weird hybrids of strat and pseudostrat epithelia in the larynx and other portions of the upper respiratory tract - metaplasia. G-4 Larynx Many have only the cored-out soft tissue, with the shell of cartilages absent. However, a little of the skeletal muscle that moved the cartilage remains, so that not all muscle is vocalis m. The vestibule is the lumen that you first enter coming from above: the ventricle is the cleft that gives definition to the vocal fold/chord.
The criteria for the vocal chord are: 1 A covering of stratified squamous ep. 2 The absence of glands in the lamina propria. 3 The wide area of CT under the epithelium, which here is elastic ligament in cross-section (the pink elastic fibers need an elastin stain to be recognized). 4 The nearby vocalis skeletal muscle fibers that alter tension in the elastic ligament.
The ventricular/false vocal fold has glands, no elastic ligament, deeper unrelated skeletal muscle, and an ambiguous epithelium, mostly of strange mixtures between typical airway and strat squam epithelia, as the airway undergoes metaplasia. Sometimes deep in the ventricle or way distant from the ventricle, one can find good pseudo-strat columnar epithelium. II. Trachea G-5 through G-7 (Figs 18.5,18.6, 18.8; Plate 67) A. mucosa 1. classify the epithelium Fig. 18.8 lining the trachea 2. note thickness of the basement membrane 3. lamina propria and its 4. extensive invasion by lymphocytes B. submucosa 1. submucosal glands Fig 18.8 C. tracheal cartilages: classify the cartilage D. trachealis muscle: classify the muscle E. adventitia G-7 Trachea Where there is a wide connective-tissue region under an epithelium, it may make sense to divide this into a lamina propria belonging with the epithelium to comprise the mucosa, and a deeper layer of connective tissue/CT to be called a submucosa (in the GI tract a layer of smooth muscle separates the two)? In some tracheas, you can see a deeper submucosa in which lie mixed sero-mucous glands. At other tracheal sites, there isn't enough thickness to be worth subdividing. A submucosa generally will have thicker collagen fibers and fewer nuclei of defensive cells. G-5 Trachea The trachealis muscle will not be present on the longitudinal section hitting the cartilage rings all at about the same point around the C. In this plane, a long. section showing the muscle would run through the gaps in the C, and no cartilage would be seen! The cross-section is of only half a C, but does extend into the gap. At the other end to the cut through the cartilage, the trachealis muscle is deeper pink than the CT, but is slightly confusing because it is in bundles and is mixed with mucous glands. III. Lung G-9 through G-11 Figs 18.7 Plates 68 & 69 A. lobar (secondary) and segmental (tertiary) bronchi (Figs 18.1, 18.7; Plate 90) 1. compare epithelium to that of trachea 2. compare cartilage arrangement to that of trachea 3. Should glands be present? Are they in your slide? 4. note arrangement of muscle in these large bronchi B. bronchioles (Figs 18.10 & 18.11; Plates 68 & 69) 1. compare epithelium to that of trachea and bronchi 2. Is cartilage present in bronchioles? [Not usually; & for exam answers, No] 3. note smooth muscle arrangement C. terminal bronchioles (Fig 18.10) D. respiratory bronchioles compare the structure of respiratory bronchioles to that of terminal bronchioles. [The respiratory bronchiole is a means of joining two geometries: the tubes conducting air and the alveolar honeycomb for gas-exchange. The respiratory bronchiole is a short connecting piece, trying to do a bit of both tasks.] E. distinguish between alveolar ducts and alveoli F. alveolar wall in light & electron microscopy (Plate 69; Figs 18.14, 18.15, Fig 18.16) 1. type I alveolar cells Figs 18.12, 18.15, 18.19 2. type II alveolar cells Figs 18.16 & 18.17 3. alveolar macrophages (dust cells) 4. continuous capillaries LUNG SLIDES need to be approached with several rules in mind. 1. Blood gets spilled when organs are cut up. Red blood cells can get into bronchioles, and other inappropriate tubes. 2. Bronchioles and bronchi have a cuboidal or higher ep. that stands out in medium power. A tube with a negligible visible lining is probably a blood vessel. 3. If there is a smooth pleural limit on one side of the section, it is from the edge of the lung, i.e., away from where the bronchi come in and branch, and bronchi are probably missing. 4. Many of these lungs were slightly pathological, and the alveolar walls have thickened, and have acquired extra white blood cells, and sometimes collections of dust-laden macrophages. Cells with bitty, fragmented-looking nuclei are neutrophils. 5. Alveolar type II cells with foamy cytoplasm are in the alveolar wall, and should be distinguished from macrophages with black specks in them and sitting on the alveolar wall. This is a distinction more easily done with EM. 6. Alveolar development lags, so keep the images of fetal lung (slide G8) separate from those of adult lung. However, the bronchi and bronchioles can be easily identified by the presence or absence of cartilage. The pale tissue around the bronchioles is mostly mesenchyme from which further tissues and development will proceed. 7. BRONCHIOLES: a respiratory bronchiole will have low cuboidal ep. and some thickness in one place around its margin, but elsewhere must have at least one site of thinned-out (sometimes protruding) wall of a thickness typical of surrounding alveoli. A bronchiole with a complete one-thickness cuboidal epithelium could be terminal, but this can only be surely known if continuity with a respiratory bronchiole is seen. 8. VERY GENERAL - a dark area running across natural boundaries may be a fold made as the section was laid on the glass slide. In a fold, you have three times the thickness of tissue to affect the light. Folds in cartilage are not vessels!

HISTOLOGY LAB 13: Urinary System

[If you find this page hard, try the alternate attack - How to appproach a kidney - on the next page] I. Kidney H-1 through H-3 A. macroscopic examination of kidney: Use textbook diagrams (Figs 19.1 & 19.3, 19.6, 19.4; Plate 70). Identify, from diagrams and text figures of sections of whole kidney, cortex and medulla, medullary rays (Fig 19.6; Plate 71 Fig 2,) medullary pyramids, and renal papillae, minor calyces, renal pelvis. Note that the fetal kidney shows its lobules on its surface Fig 19.5 B. capsule H-1 Fig 19.2 C. renal cortex 1. renal corpuscles (Plate 70 Fig 2; Plate 72 Figs 3 & 4; Fig 19.7 (Fig 1.2 shows basal laminae, as does your PAS-stained slide) a. Bowman's capsule (1) parietal layer (Fig 19.7; Plate 71 Figs 3 & 4) (2) visceral layer (podocytes) (Figs 19.8, 19.11, 19.12) b. glomerulus Fig 19.8 makes the microscopists' point that what the physiologists call the glomerulus is only the podocyte-clad tuft of capillaries, so beware the terminology c. afferent and efferent arterioles: be able to identify afferent arterioles when seen attached to a macula densa Fig 19.7b d. vascular and urinary poles Fig 19.7; Plate 72 Fig 4 e. mesangial cells & matrix Figs. 19.7, 19.9, 19.12 Know them on TEMs. 2. components of the uriniferous tubule a. proximal convoluted tubules & proximal straight tubules Plate 72 b. distal convoluted & distal straight tubules (Fig 19.17; Plate 72 Fig 1 & 2) Exam - Know the difference between proximal & distal tubules in TEM see Figs 19.15 & 19.18 c. cortical connecting tubules or ducts 3. juxtaglomerular apparatus (Figs 19.7(a) & (b); Plate ) a. juxtaglomerular cells (modified smooth muscle cells of afferent, and occasionally efferent arterioles; and recognize in EM Figs 19.8 & 19.10) b. macula densa (modified part of the distal straight tubule) (Fig 19.7; Plate 72 Fig 3) D. medulla (Figs. 19.3, 19.18, 19.4; Plate 71 Fig 2; Plate 73 ) 1. components of the uriniferous tubule a. proximal straight tubules b. distal straight tubules c. loop of the nephron (includes the above two elements; plus the thin segment, for which read Textbook p. 619 and see Fig 2.1a; Plate 73 Fig 1) d. collecting ducts/tubules The terminology is lax Plate 72 Fig 2, & Plate 73 Fig 1 e. papillary ducts (ID from proximity to papilla and their width, if the papilla is present E. blood vessels Know the course of blood vessels and ID arcuate arteries Plate 70 Fig 2 II. Ureter H-4, H-5 (Plate74) A. mucosa 1. classify epithelium lining the ureter 2. lamina propria B. muscularis: note the arrangement of layers C. adventitia III. Urinary bladder H-6, H-7 (Fig 19.20 & 19.21; Plate 75) A. mucosa 1. Epithelium lining the urinary bladder? Stretching devices - Figs 19.23, Figs 19.24, 19.25 2. lamina propria B. muscularis: read about arrangement of muscle layers at Plate 75 C. adventitia/serosa Why does the u. bladder have both? It's fundamental! IV. Urethra, male A. prostatic portion K-13, K-14 1. classify the epithelium lining this portion of the urethra, if you can 2. note surrounding prostate - the region prone to benign prostatic hypertrophy. B. membranous portion: no slide C. penile (spongy or cavernous) portion K-15, K-16 ( Fig 21.30) 1. classify epithelium lining lumen, if you can 2. Mucosal glands of Littre are missing from our slides. V. Urethra, female: no slide - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
HOW TO APPROACH A KIDNEY Cautiously, because although the individual uriniferous tubule makes sense, when a million of them are packed together at different levels, fixed imperfectly, and stained in an unbalanced way (plus, maybe, a little pathology), the images can become difficult to interpret.

Look at all the kidney slides against a white background and using the eyepiece, reversed, as a low-power magnifier. Questions: Is it a unilobar animal kidney? If it is human multilobar kidney, do you have more than one lobe present and how small is the piece, e.g., does it go out to the capsule? How far towards the hilus does it go? Where are the cortex and medulla? Is the medulla intact? How is the section stained - H. & E. , PAS, a trichrome? See below for how this information can help.
If the kidney is unilobar, or you have only part of one lobe of a multilobar one, you will not see renal columns. If the apex of the pyramid is cut off, you are missing the papilla and with it the papillary ducts. Some structures, e.g., the renal sinus and its calyces, are best appreciated by the gross anatomist or pathologist doing a conventional dissection, and working with a complete kidney. With PAS staining, the individuality of the nephrons and collecting tubules shows up because the basal laminae are revealed, and the staining shows up the microvillous border of the proximal tubules.

To start the microscopy, use the piece of human kidney stained with H. & E. Go to the cortex and search along to a place where the renal corpuscles and surrounding labyrinth are distinct from the parallel elements of the medullary rays. The corpuscles contain a capsular space, usually visible, and the enclosing capsule lined by the parietal epithelium, seen only as flattened nuclei of the simple squamous epithelial cells. In the glomerulus all you can say is that the many nuclei have to belong to podocytes (the visceral epithelium), endothelial cells and, towards the vascular pole, mesangial cells. The cells cannot be reliably distinguished in these specimens with only high-dry mag., but with TEM (& SEM) it's easy.
The task of telling afferent from efferent arterioles is not for novices. There is a difference in caliber, but one needs to see both arterioles at the same time. The most one should try to say is that the vessel fastened to a macula densa is likely to be an afferent arteriole.

To build confidence one can work through the structures that give no trouble, before tackling anything harder. The majority of the tubules cut in cross & oblique section around the glomeruli have to be prox. convoluted tubules. Next, mixed in with these will be a few distal convol. tubule profiles, with wider lumens, cells staining less red, no brush border and more nuclei per cross-section. Scan quickly over a number of corpuscles until you find a JGA with a macula densa. The other side of the distal tubule to its macula densa will be typical distal tubule. Thus, in the cortical labyrinth you have reliably identifiable prox. & distal tubules to go back and check with, when you are later looking for straight proxs. and distals in medullary rays and the outer medulla.

The third easy tubule is the collecting duct. Find the cortico-medullary junction and cruise down and back through the medulla with the idea of assigning one chunk to outer zone, the other to inner. In the inner medulla, find a collecting duct - pale cells, distinct cell outlines, some luminal bulging, & a significant lumen. Go down into the papillary region, if it is present, and trace from the surface inwards the papillary ducts. (In the large slide, the epithelium of these ducts is grotesquely flattened from excess pressure and all the tubules are distended - artefact).

The outer medulla is the place to hunt among the many profiles for thin segments. The difficulty here is that they are small and mixed in with a lot of other things. The epithelium is simple squamous, but definitely more visible than endothelium of capillaries. While you are in this region of outer medulla look for straight parts of prox. and distal tubules. (You may need to go back to the cortex for a check on prox.-distal differences.) One problem is that the tubules of your chosen part of the medulla may be cut at an unfavorable angle; if so, move around. You will not see loops (Henle's) of nephrons, only the components - straight distals & proxs. & thin segments. Now, you can try for the collecting ducts in the medullary rays, where they will be sparse and central, so that the wider cuts through rays are better bets; and for the connecting tubules (CTs) coming to rays from the labyrinth. CTs have a lower, paler cuboidal ep. than distal tubules. They are an emaciated version of the collecting ducts seen deep in the medulla: if you cannot find them & 'ray' collecting ducts, never mind.


HISTOLOGY LAB 13: Male Reproductive System

I. Testis K-1, K-2, K-3 (Figs. 21.4, 21.5, 21.3; Plates 82, 83) A. tunica albuginea K-1, K-3 B. mediastinum testis K-5 (Figs 21.2, 21.19; Plate 83 Fig 2) may be missed by the cut on your slide. You are looking for the triangular-shaped wedge of connective tissue extending into the testis from the capsule. There has been a blockage downstream so that the Rete testis - the collective name for the delta-like spaces running through the Mediastinum - are very dilated. C. seminiferous tubules K-5, K-2 K-5 is better for cell types, but Leydig cells are few and far between 1. seminiferous (germinal) epithelium (Figs 21.5 & 19b.14; Plate 82) a. Sertoli cells (Figs. 21.4, 21.16, 21.17) (Note the prominent nucleolus) Plate 83 Fig 1 shows immature Sertoli cells b. proliferative cells Figs. 21.5, 21.6; Plate 82 (1) spermatogonia (2) primary spermatocytes (3) secondary spermatocytes (4) spermatids (early [small, round nuclei] and late [smaller, darker, elongated nuclei]) (5) spermatozoa (if free in the lumen) Fig. 21.11, 21.12 D. interstitial cells of Leydig K-2, K-3 (Figs 21.5b; Plate 83 inset) K-2 testis. Leydig cells are often hard to find. Beware of taking a glancing cut through the edge of a seminiferous tubule showing only spermatogonia for Leydig cells outside the tubules. II. Male duct system (Figs. 21.1 & 21.4) A. seminiferous tubules K-2 B. straight tubules (tubuli recti) K-1, K-5 if you have them (warning: some K-1s have no mediastinum), K-5 Fig 21.19b C. rete testis K-5 (Fig 21.19) [Rete is the labyrinth of epithelium-lined spaces within the mediastinal connective tissue. The idea is superimposed on that of the other collective concept - the mediastinum testis]] D. efferent ducts K-6 (Fig 21.21; Plate 84) E. ductus epididymis K-7 (Figs 21.22 , 21.23, 21.24; Plate 84) with spermatozoa in the lumen. Note the coiling of the one epididymis gives many cut profiles in the section. F. ductus/vas deferens K-8, K-9 (Fig 21.25 ; Plate 85) 1. mucosa 2. muscularis 3. adventitia with blood vessels G. ejaculatory duct (may be visible in some prostate gland slides) III. Accessory sex organs A. seminal vesicles K-10, K-11, K-12 (Fig 21.26; Plate 87) Some slides are from animals, and are very unlike human seminal vesicle B. prostate gland K-13, K-14 (Fig 21.28; Plate 86) 1. glands & fibromuscular stroma 2. urethra, maybe (many slides miss the urethra and ejaculatory ducts 3. prostatic concretions (corpora amylacea) C. bulbourethral (Cowper's) glands no slide, but see Fig 21.29 D. penis K-15, K-16 (Figs 21.30, 21.31) The penis is mounted sideways on the slide so that the urethra - useful for initial orientation - is off to one side 1. corpus spongiosum (corpus cavernosum urethrae) a. urethra (1) glands of Littre‚ (rare in our slides) 2. corpora cavernosa

HISTOLOGY LAB 14: Female Reproductive System System

I. Ovary L-1, L-2 The L3 ovary of dog is confusing, because of the number of corpora lutea present. To produce a litter, the bitch has multiple, synchronous ovulations, with each follicle leaving a corpus luteum - the large pale structures, bulging out from the surface, and crowding out most of the ovarian follicles
The corpora lutea also have the large pale cells, appropriate to steroid synthesizers, but these are all granulosa lutein cells.
Another difference from human corpus luteum is that there is no central blood clot. However,there is a clear distinction between ovarian cortex and the central medulla, with its many prominent vessels
A. general structure (Fig. 22.2; Plate 88) 1. tunica albuginea an unfortunate term because the ovarian covering is negligible in comparison to that of the testis 2. cortex 3. medulla B. follicles (Fig. 22.3 through 22.7; Plates 88, 89) Many of our ovary slides have few follicles, and no visible antral follicles, but do have extensive glandular tissue. Look at the demo scope on the side for good follicles. Be able to describe them - primordial, unilaminar, mulilaminar-no antrum, small antral, large antral, antral large to the point of bulging the ovarian surface - then apply primary, secondary, tertiary, Graafian - as indicated in the theory. 1. primordial follicles Fig. 22.3 a. primary oocyte b. follicle cells 2. growing follicles a. early primary (unilaminar) b. late primary (multilaminar) Figs. 22.5, 22.6 (1) stratified epithelium (2) zona pellucida Know the EM view as well c. secondary (antral) Fig. 22.6 (1) antrum and liquor folliculi (2) theca (a) theca interna (b) theca externa (3) cumulus oophorus (4) granulosa cells d. mature (Graafian) follicle (really big) Fig 22.7 3. atretic follicles Plate 89 Figs 3,4 & 5 The granulosa cells are shedding into the antrum, and are breaking up C. corpus luteum L-3 (Plate 90; Fig. 22.11) 1. granulosa lutein cells 2. theca lutein cells (not to be found in the animal ovaries) D. corpus albicans Fig. 22.13 - small pale pink areas of connective tissue. Human ones are larger and more prominent II. Uterine tube/Oviduct L-4, L-5 (Fig 22.15; Plate 91) A. general structure 1. intramural (interstitial) part 2. isthmus we do not have slides of 1 & 2 3. ampulla Fig. 22.15 4. infundibulum and fimbria (only some slides have fimbria - see demo) B. histological plan 1. serosa 2. muscularis 3. mucosa a. epithelium (ciliated simple columnar) Fig. 22.15b b. lamina propria III. Uterus L-6, L-7, L-8, L-9 (Figs 22.16, 22.18; Plates 92, 93) A. gross structure 1. body and fundus 2. cervix L-10 (Figs 22.21, 21.22, 21.23, 22.29; Plate 94) a. epithelial transition (simple columnar to strat. squam.) Fig. 22.23 On many of our slides, the transition is obscured by missing epithelium, or variants on the typical epithelia, and by the deep cervical glands B. histological structure 1. serosa/perimetrium 2. myometrium 3. endometrium a. uterine glands b. functionalis zone the zones are judged rather subjectively under low power, where the full thickness of the endometrium can be seen c. basalis zone (next to the muscle, and in about a 1 to 4 relation to the functionalis) C. menstrual phases (Figs 22.16, 22.18; Plates 92, 93) 1. proliferative phase L-6 (Straighter glands; denser stroma) 2. secretory phase L-7 (Crinkly, longer glands; looser stroma) 3. menstrual phase L-8 IV. Vagina L-11, L-12 (Figs. 22.27, 22.28; Plate 97) A. mucosa 1. epithelium (somewhat atrophied as a stratified squamous ep. because the hormonal drive is long gone) 2. lamina propria (Are there glands present?) B. muscularis (not easily detected - the hallmark of the vagina is the lack of outstanding features and layering) V. Mammary glands (Figs 22.32 through 22.35; Plates 98 & 99) A. inactive L-13 Note the few surviving ducts in much dense connective tissue B. active L-14 VI. Placenta L-15 (Figs. 22.25, 22.26; Plates 95, 96) Try to work out: which is the chorionic-plate side (like umbilical cord) and which is the maternal decidual side torn away from the muscular uterine wall; which are the major stem villi, and which are the fine frondy tertiary ones surrounded by the maternal blood space; and what is fibrinoid - the scattered red protein deposits.

HISTOLOGY LAB 15: Oral Structures

A. SALIVARY GLANDS I. Secretory units: E-22 has all of these components E-22 SUBMANDIBULAR GLAND is mostly serous so that the background is dark and granular. Against this background one sees many pink round intra-lobular ducts - a surprisingly high number. Interlobular ducts are in obvious connective tissue of septa dividing the gland into lobules. The INTER-lobular ducts have columnar epithelium and are accompanied by blood vessels. The intercalated ducts are very small. One looks for a small pink structure smaller than a single serous acinus, and contrasting with it. There should be two or more small elongated nuclei in the pink duct cytoplasm. A good place for intercalateds is near to intralobulars because the former have eventually to reach the latter. A. serous B. mucous C. serous demilunes (Plate 47; Fig 15.28) II. Ducts: E-22 and all other salivary gland slides A. excretory B. striated (secretory) C. intercalated (small & inconspicuous) III. Myoepithelial cells (identify on EMs only) (Figs.15.21,.22,.23) IV. Histology of the major salivary glands Fig 15.28 A. parotid (Plate 48) 1. secretory units (Fig. 20) 2. distribution of ducts 3. fat cells often present B. submandibular (Plate 47; Fig. 15.22) 1. secretory units 2. distribution of ducts C. sublingual (Plate 49) 1. secretory units 2. distribution and number of ducts IV. Minor salivary glands (identified by position: only if you know what the organ is, can you name the gland) A. labial M-1 B. buccal M-2 C. palatal A-19 D. lingual M-3, M-4, M-5 1. posterior mucous glands of Weber 2. posterior serous glands of von Ebner 3. anterior glands of Blandin-Nuhn: no slide
If you have a dark serous gland with no islets but a lot of ducts, search over it very carefully for any mucous secretory units (they do look different from fat cells under high power) in order to distinguish parotid from submandibular.

DUCTS are named for postion, function and appearance so: interlobular/excretory versus intralobular/secretory/striated (some of our slides are cut to miss interlobular ducts). "Striated" for the basal mitochondria and infoldings for ion transport so that the secretory duct can alter the secretion, in contrast to the excretory or drain-pipe kind.

LABIAL, BUCCAL, etc. minor salivary glands. The ID requires using two or three magnification powers: to be sure of the gland (in newborns they look serous, because mucus has not yet built up), and to see that the organ is lip, cheek, palate, or tongue. [Our only palate is a fetal sagittal-face section.] Tongue is easy from the papillae. Cheek has more adipose tissue than lip, and lacks a red margin. The glands will be on the mucosal side below the thick strat squamous epithelium.

Let's get serious about SEROUS.

SEROUS: 1. applied to glands and certain glandular cells 2. signifies major protein secretion occurring but not of mucous glycoprotein 3. examples - pancreatic acinar cells, gastric chief cells, parotid secretory cells

SEROUS: a. relating to serous body cavities - pleural, pericardial, peritoneal b. mobile tubes or theirenlargements in these cavities have an external layer - the t. serosa c. Tunica serosa and serous membrane are both covered by simple squamous epithelium (mesothelium) to allow lubricated movement (serous fluid lubricates) d. inflammation, interruption of the mesothelia, & fusion of the two connective tissues --> adhesions, restricting movement, and impairing function

 

B. ORAL MUCOSA AND TONGUE I. Tongue M-3, M-4, M-5 (Figs 15.3, 15.4 and Plates 45 and 46) A. papillae 1. filiform 2. fungiform 3. circumvallate (vallate) 4. foliate (no slide) B. taste buds (Figs. 15.5) [Fungiform papillae also may have taste buds, but on their top, not lateral, surface.] C. lingual salivary glands M-3, M-4, M-5 1. anterior glands of Blandin-Nuhn: no slide 2. posterior serous glands of von Ebner 3. posterior mucous glands of Weber are on some slides TEXTBOOK Plate 46, Fig 1 shows foliate papilla. Forget this image - it is only seen in animals. Fungiform papillae are in the section of anterior tongue amongst many spiky ragged FILIFORM papillae II. Lip M-1 (Plate 44) Many of these slides are from newborns, so the oral mucosa is very thick, the red margin is narrow and hard to make out, and the skeletal muscle is immature, which may hold for the cheek as well. Also, the minor salivary glands have not yet become pale with accumulated mucus.] A. cutaneous surface B. mucosal surface C. vermilion border/red margin (zone) D. labial minor salivary glands M-1 LIP can be difficult. Some sections are cut through at the edge of the mouth, and do not show the lip in full. The sample is from a late fetus so that the red margin is unusually short. It is from where the skin's hair follicles and glands stop to where the epithelium becomes thick. The labial mucosa is protected by its thickness and by the mucus secreted by its and other glands. Since the gland cells are immature, they look dark and "serous", because very little pale mucus has yet accumulated in them. The glands lie deep to the epithelium and may have one or two ducts visible. M-5 Fungiforms may have pale oval TASTE BUDS set in the epithelium facing the oral cavity. CIRCUMVALLATE papillae are in the posterior tongue M-3 where filiforms are petering out. Their taste buds are in the side facing the trench. Below the trench are dark serous von Ebner lingual glands, but also mixed in with posterior core muscle of the tongue are pure mucous posterior lingual glands. Inside a lingual papilla, e.g. circumvallate, the epithelium will have its own small connective-tissue papillae protruding up into it. An oblique section through one of these might look like a taste bud. However, a taste bud is set within the thickness of the epithelium on the trench-facing side, and has more nuclei and a different look from a CT papilla III. Cheek/Buccal organ M-2 A. cutaneous surface B. buccal mucosal surface C. buccinator muscle D. buccal minor salivary glands (if present) M-2 CHEEK is also immature, so that the skeletal muscle in the core is un-developed and looks odd. The keys to cheek are skin outside, thick strat squam ep inside, and (to separate it from lip) more adipose tissue under the skin and NO RED MARGIN. Only if you are at low power and can identify the cheek as lip/cheek, can you say that the mucosal glands are labial/buccal.


HISTOLOGY LAB 16: Esophagus and Stomach

A. ESOPHAGUS Keep in mind the general structure of tubular organs and compare each digestive organ studied to the generalized plan Fig 16.1, noting functional and anatomical specializations. I. Esophagus: note all the following characteristics of upper, middle and lower parts of the esophagus E-1, E-2, E-3 (Fig.16.2, 16.3, 16.4; Plate 50) A. strat. squamous epithelium lining the esophageal lumen B. lamina propria E-1, E-3 1. esophageal cardiac/mucosal glands might be present The glands of the esophagus are easy to recognize, but hard to find. Many of our specimens have no glands at all. Those that are present are likely to be submucosal. Don't waste time hunting C. muscularis mucosae D. submucosa 1. esophageal glands submucosal/proper E-3 (may be present) 2. neuron cell bodies of Meissner's submucosal plexus may be present E. muscularis externa: type of muscle varies in proximal, middle and distal portions of the esophagus. 1. neuron cell bodies of myenteric (Auerbach's) plexus) F. adventitia II. Stomach: note variations in various portions - cardia, fundic/corpus & pyloric - of the stomach Fig 16.5 A. mucosa of fundic/body regions E-6, E-7 (Plate 53) 1. mucous gastric epithelium lining lumen 2. gastric pits 3. gastric glands proper (fundic glands) Fig 16.8 a. chief/peptic cells (should be blue in a well-balanced H&E prep.) b. parietal cells c. neck mucous cells/mucous neck cells d. enteroendocrine cells (rare, with very pale cytoplasm, & more noticeable towards the base of the glands) B. pyloric mucosa E-8 (Figs 16.15, 16.16; Plate 54) 1. epithelium lining lumen 2. gastric pits (deeper than in fundus) 3. pyloric glands mostly mucous (shorter than in fundus) 4. lamina propria 5. muscularis mucosae C. cardiac mucosa E-5 Figs 16.4 & 16.6; Plate 51 1. epithelium lining lumen 2. gastric pits 3. cardiac glands (chief & parietal cells absent) D. esophageal-gastric or gastro-esophageal junction: note epithelial transition from esophagus to stomach E-4 (Fig 16.6; Plate 51) E. submucosa E-6 E-7, E-8, E-9 F. muscularis externa 1. neuron cell bodies of myenteric plexus (Auerbach's plexus) G. serosa F. pyloric sphincter E-9 enlarged external circular muscle

HISTOLOGY LAB 16: Small & Large Intestines

A SMALL INTESTINE I. Pyloro-duodenal junction: note epithelial transition at this junction, E-9 Plate 54 E-9 PYLORODUODENAL JUNCTION is folded so that the junction is on a bend. Three other factors make this section difficult. There is more pylorus than duodenum. The villi of the duodenum have lost their epithelium so that the key criterion - goblet cells - is missing. [The epithelial loss resembles the "de-gloving injury" workers around industrial machinery sometimes suffer.] The villi, consisting of just of the lamina- propria core, are barely identifiable. Third, the Brunner's submucosal glands do not stop precisely where the villi stop, but continue a little way under the muscularis mucosae of the pyloric stomach. This adds to the mucus released here to counteract gastric acid and pancreatic enzymes, but is not "textbook correct". II. Duodenum E-10 Fig 16.19; Plate 55) A. mucosa 1. epithelial lining of duodenal lumen a. absorptive cells/enterocytes Figs. 16.12, 16.13 b. goblet cells Fig. 16.15 2. villi 3. intestinal glands (crypts of Lieberkühn) a. stem and differentiating cells b. enteroendocrine cells Fig. 16.25 c. Paneth cells (Fig. 16.24) [Granular, eosinophilic, defensive cells] 4. lamina propria a. lacteals (Fig.16.12; Plate 78) 5. muscularis mucosae B. submucosa 1. duodenal submucosal glands (Brunner's glands) Fig 16.27 2. Scan for any neuron cell bodies of the submucosal plexus (Meissner's plexus) in this and other gut slides C. muscularis externa 1. layers and orientation of smooth muscle fibers 2. neuron cell bodies of myenteric plexus (Auerbach's plexus) D. serosa/adventitia (where is there an adventitia?) III. Jejunum E-11 (Plate 56) A. mucosa: compare mucosa of jejunum with that of other parts of the small intestine 1. identify same cell types as seen in duodenum 2. lamina propria: compare with duodenum 3. muscularis mucosae: compare with duodenum B. submucosa: compare with duodenum and note absence of submucosal glands in jejunum C. plicae circulares (valves of Kerckring Fig. 16.17) - need a good length of longitudinal section: folds of mucosa and submucosa which are much more prominent in jejunum than in other areas of the small intestine D. muscularis externa E. serosa The duodenum and ileum can be positively identified (Brunner's gland and Peyer's patches, respectively). The jejunum has neither, but their absence is suggestive, but not diagnostic of jejunum: correct answer "small intestine (jejunum?)" IV. Ileum E-12, E-13 (Plate 57) A. mucosa: compare ileal mucosa to that of other parts of the small intestine 1. identify same cell types as seen in duodenum 2. lamina propria 3. muscularis mucosae B. submucosa: note absence of submucosal glands and presence of aggregations of lymphatic nodules (Peyer's patches) Fig 16.20 C. muscularis externa D. serosa Slide E-12 is human ileum in odd-numbered slide sets, monkey in even-numbered sets. Most monkey slides demonstrate Peyer's patches. B. LARGE INTESTINE I. Large intestine or colon E-14, E-15 ( Figs 16.32 & 16.33; Plate 58) A. mucosa: compare colonic mucosa to mucosae of small intestine regions 1. cell types a. absorptive cells/colonocytes (termed absorptive cells in the textbook) b. goblet cells (note their abundance) c. enteroendocrine cells 2. lamina propria 3. muscularis mucosae B. submucosa: no glands C. muscularis externa: note modifications of this layer - teniae coli for longitudinal muscle layer D. adventitia/serosa E-14 is not a precise cross-section of the large intestine because the outer longitudinal layer of the muscularis externa does not go thin, and then fatten out into a tenia coli, but looks all about the same thickness. Interpretation - this is an oblique cut that stays within one tenia. I'll find a classic view for the review. II. Vermiform appendix E-16, E-17 (Fig 16.35; Plate 89) A. mucosa: Note variability in presence of lumen & amount of lymphoid tissue between appendices from young and old individuals. 1. lamina propria 2. muscularis mucosae may be disrupted by lymphoid tissue B. submucosa C. muscularis externa D. serosa III. Recto-anal junction E-18, E-19 (Fig. 16.36 & 16.37; Plate 60) A. mucosa: note epithelial transition at this junction. It varies & may include cuboidal forms Fig 16.37b B. anal sphincters: internal and external are hard to distinguish because these skeletal muscle fibers are embryonic and small, and are not that different from the smooth muscle.

HISTOLOGY LAB 17: Liver, Gallbladder & Pancreas

I. Liver E-27 through E-32 A. The liver is divided into four lobes and the lobes are further subdivided into numerous, but far less obvious lobules. Fig 17.1 B. hepatic lobule (classical hepatic lobule Fig 17.3): identify a hepatic lobule by locating the central vein (terminal hepatic venule) which occurs in the center of a lobule. (Figs. 17.4, 17.2; Plates 61 and 62) C. portal canals (portal areas) (Fig. 17.1; Plate 61) occur at junction between classical hepatic lobules Fig. 17.3. Identify the structures found in a portal canal. The term 'portal triad' is often used to describe a portal canal, but a portal triad only includes the first three of the following structures 1. hepatic arteriole 2. portal venule (vein) 3. interlobular bile ductule/duct 4. lymphatic vessel (skip - difficult to see) D. hepatocytes: these large cells constitute the vast majority of the cells of the liver. They contain considerable glycogen (middle inset Fig on the cover of textbook) see slide E-32; and they are supported by a network of reticular fibers (see slide E-31). E. hepatic macrophages/von Kupffer cell ID these cells in electron micrographs Fig 17.9 & Plate 62 Fig 2 F. Identify the following structures in electron micrographs: 1. bile canaliculi Figs 17.13b & 17.14 2. perisinusoidal space of Disse (Fig. 17.9, 17.10; Plate 85) 3 stellate or fat-storing cells of Ito Fig 17.9 II. Gallbladder: E-33, E-34 Fig 17.16 & Plate 63 A. mucosa 1. epithelial lining of the gallbladder 2. lamina propria B. muscularis C. adventitia/serosa Rokitansky-Aschoff sinuses ( Fig. 17.18) are invaginations of the lining which may appear to be separate eithelium-lined structures III. Exocrine pancreas E-24 through E-26 (Fig 17.22; Plate 64) A. pancreatic acini Figs. 17.20, 17.21 B. duct system 1. intercalated ducts Fig 17.20a and centroacinar cells 2. intralobular ducts 3. interlobular ducts Fig 17.22 and the endocrine C. pancreatic islets of Langerhans Figs. 17.23, 17.24 E-26 Pancreas slide. For ISLETS, look with the glare eliminated under low or medium power. They will be paler and more of a poorly organized clump than the surrounding dark acini. Coming to each acinus is a tiny intercalated duct - intercalated = put in between the acinus and the intralobular ducts. However, these IC ducts are thrust actually inside the acinus. Because of differing section cuts through the various acini, only a few acini will show the central one or two flattened light centroacinar cells situated in the center of the dark acinus. Occasionally one can see continuity between these cells and the intercalated ducts outside the acini. --------------------------------------------------------------------------

HISTOLOGY LAB 18: Endocrine Organs

I. Thyroid J-5 and J-6 (Fig 20.12; Plate 79) A. follicles 1. Describe epithelium, and correlate epithelial appearance with functional stages of hormone synthesis and secretion. 2. Note staining of colloidal material in the follicles. B. parafollicular cells (C-cells) Fig 20.14 are not visible in class slides FOLLICLE versus CYST - structurally the same (epithelial cells around what they have secreted), but 'cyst' implies an abnormal process, 'follicles' are normal developments. [Remember that, in gross anatomy, 'cyst-' is a prefix signifying urinary bladder, e.g., cystitis] II. Parathyroid glands J-7 (Fig 20.15; Plate 79) A. cell types 1. principal or chief cells 2. oxyphil cells (clumped or solitary) J-7 has oxyphil cells, but they are almost all at one end of the section. When found, ours are better than the text's - not overstained with hematoxylin III. Adrenal (Suprarenal) glands J-8 (Fig 20.16, 20.21; Plates 80, 81) A. suprarenal cortex 1. zona glomerulosa 2. zona fasciculata 3. zona reticularis B. suprarenal medulla 1. chromaffin cells almost all the cells in the medulla 2. neuron cell bodies of sympathetic NS (rare, only on a few slides) Note that the fetal adrenal develops a cortex which does not last, because it is in an endocrine context which includes the placenta Fig 20.23 and pp. 668-669 IV. Hypophysis (pituitary gland): Use text Fig. 20.2 & Plate 76 Fig 1, along with slide J-1, to orient yourself to the gross morphology of the hypophysis; identify pars distalis, pars intermedia, pars nervosa and pars tuberalis (if present) using the naked eye, or a microscope objective reversed and used as a magnifying glass, by holding it very close to your eye A. adenohypophysis 1. pars distalis J-1 through J-3 (Plates 76 & 77) a. chromophils Fig 20.6 (1) acidophils (2) basophils b. chromophobes 2. pars intermedia J-1 a. Note location between pars distalis and pars nervosa b. Are there follicles or cysts in this region? 3. pars tuberalis J-1 a. Compare cells here to cells in pars distalis B. neurohypophysis J-1 1. pituicytes (their processes are unseen, but most of the nuclei belong to pituicytes) 2. unmyelinated axonal processes (the pale majority of the tissue) 3. Herring bodies -- secretion collected in single axons (small round eosinophilic bodies Plate 77 Fig 2, unless the secretion is stained for specifically as in Plate 77 Fig 3 J-1 PITUITARY Depending on the cut you may have no pars tuberalis and sometimes not much pars nervosa. The pars intermedia or intermediate lobe (Fig 20.7) is easier to make out on low power and sometimes extends small clumps of cells into the pale fibrous pars-nervosa tissue. The nuclei in the pars nervosa mostly belong to pituicytes, except for a few endothelial nuclei V. Pancreatic islets (of Langerhans) E-24, E-25, E-26 (Fig 17.22; Plate 64) A. alpha cells Figs 17.23 & 17.24 B. beta cells (in less need of specific markers, since they have to be in the majority) C. delta cells VI. Pineal organ (no slide) (Fig 20.10; Plate 78) A. cell types 1. pinealocytes 2. glial cells B. brain sand (corpora arenacea, acervuli cerebri) [Based on deposited calcium salts, not silica! Makes the older pineal gland stand out on X-ray & CT of the brain.] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - BEWARE! REDS in the Endocrines 1 Anterior pituitary acidophils stain red with the eosin of H&E 2 Pituitary basophils stain pink-red with PAS because they make glyoprotein hormones. The clue on the slide is that basal laminae are also stained with PAS 3 A RED TAG can be attached to an MoAb (monoclonal antibody) raised against a particular hormone, e.g., calcitonin, or insulin. Then, to identify the cells needs more information. Thus, a blue counterstain shows enough of the thyroid follicles for the few red cells outside the follicular epithelium to have to be C cells. In the pancreas, if the red cells are in the majority, they have to be the ones where the MoAb was against insulin, revealing the 'red' cell-type as BETA cells

HISTOLOGY LAB 19: Blood and Hematopoiesis

Histology of stained blood smear: A-1 (Fig 9.1; Plates 16 & 17 & use subsequently) I. FORMED ELEMENTS 1. erythrocytes/RBCs Figs 9.2, 9.6 2. leukocytes [Use your knowledge of relative numbers: neutrophils have to be met most often, lymphocytes next most frequently. If you keep on seeing a type of cell in normal blood, these cells cannot be the rare basophils or eosinophils. Next, beware of mistaking the clumped chromatin in lymphocyte nuclei for the granules of basophils. a. granular leukocytes (1) neutrophils Fig 9.7 (a) Barr bodies (in women's neutrophils) Fig 2.56 (2) eosinophils Fig 9.10 (3) basophils Fig 9.11 b. agranular leukocytes (1) lymphocytes Fig 9.12 (2) monocytes Fig 9.3 3. platelets (thrombocytes) Fig 9.15 Plate 16 II. ELECTRON MICROSCOPY of blood cells (use above Figs) A. erythrocytes B. leukocytes 1. granular leukocytes a. neutrophils b. eosinophils c. basophils 2. agranular leukocytes a. lymphocytes b. monocytes C. platelets III. Histology of stained BONE MARROW smear A-2 (Fig 9.16 misleads: It is a section & is stained with H&E) A. Sinusoids/sinuses [Important, but not preserved in a smear] B. Cells of the erythroid lineage far outnumber those of the myeloid and megakaryocytoid lineages 1. megakaryocytes Fig. 9.14 a. megakaryocytes in light microscopy A-2 b. megakaryocytes in electron microscopy (Fig 9.14) C. Remember that marrow stromal cells (which resemble fibroblasts) play a key role in controlling hemopoiesis, although we are not asking you to identify them. The textbook is way behind the times in naming them as adventitial or reticular cells. A-2 MARROW is a smear so, although the occasional megakaryocyte can be found, the sinusoids cannot be recognized. Know sinusoids, platelets & megakaryocytes on an EM view. A-2 BONE MARROW smear. Many examples have a surprisingly low number of megakaryocytes. Identify the irregular lumps of purple stain (artifact), while looking for a large purple cell, which, on high power view, has an odd lumpy nucleus.

HISTOLOGY LAB 19: Lymphoid Organs

I. Lymph node D-4, D-5, D-6, D-7 (Figs. 13.15, 13.18, 13.19, 13.23; Plates 33 & 34) A. reticular connective tissue framework D-6 B. capsule C. cortex and medulla D. germinal centers E. paracortical zone (requires distinguishing cortex from medulla, then the paracortical zone is the thin, poorly demarcated, merging territory) F. sinuses 1. subcapsular (marginal) sinus 2. cortical sinuses 3. medullary sinuses D-7 This node is from the mediastinum of someone with very black lungs. The macrophages are laden with particles in the subcapsular sinus and the medulla, leaving the cortex more blue in between. D-5 has a small node on which the medulla cannot be made out. Use the larger node. II. Spleen D-8, D-9, D-10, D-11 (Figs 13.29, 13.30; Plates 35 & 36) A. capsule (not seen on most slides) B. connective tissue trabeculae C. red pulp and white pulp respectively reddish and blueish in H&E D. blood-flow pattern Fig 13.31 1. splenic artery 2. trabecular arteries 3. central arterioles 4. pulp arterioles 5. sheathed arterioles 6. splenic sinuses/sinusoids 7. pulp veins 8. trabecular veins (endothelium-lined spaces within trabeculae, but lacking major smooth muscle) 9. splenic vein E. splenic 'cords' [When you can see sinusoids, the red-pulp tissue through which they run looks cord-like in longitudinal view; Plate 36 is less convincing.] F. periarterial lymphatic sheath (PALS) G. splenic nodules [Dilations of white pulp along the PALS: see Plate 35 Fig 3] WP = SN + PALS White pulp comprises the splenic nodules and the PALS. Note that they have, respectively a preponderance of B vs. T lymphocytes (for theory) but do not worry about distinguishing them for the lab exam. Nodules are plump and, if the germinal center is hit, are easily identified. However, an edge cut through a nodule could be mistaken for the narrower width of the PALS. D-9 the spleen is compressed so that sinusoids cannot be made out. Also, the white pulp is only slightly more blue than the red pulp. D-4 has similar compression, making the it hard to distinguish cords from sinuses in the medulla D-8 spleen has empty sinusoids, so that the sinusoid-"cord" distinction can be made. Cord only has meaning as the strip between longitudinally cut sinusoids; otherwise it is the 'cheese' around the spaces. Two terms that can confuse. The MANTLE ZONE is a region sometimes visible as a cap of densely packed dark B cells at one side (towards the lumen for gut nodules) of lymphoid nodes/follicles wherever they occur. The MARGINAL ZONE is only in the spleen, between the white pulp and the red pulp. There are many dendritic APCs here. [The mantle zone is the source of a kind of leukemia - the "mantle-zone" lymphoma] D-8 spleen. The trabecular arteries are just endothelium-lined separations of the trabecular collagen; the trabecular arteries should be smaller, and have a distinct ring of smooth muscle. III. Thymus D-12 (Figs 13.24 & 13.25; Plate 37) A. organization 1. lobules 2. cortex and medulla B. components 1. cells a. lymphocytes/thymocytes b. epithelial-reticular cells 2. thymic (Hassall's) corpuscles C. identification of young vs. adult (involuted) thymus D-12 has both young & old thymuses IV. TONSILS A. lingual tonsils D-2 [Lingual tonsil - A relatively thin layer of lymphoid tissue is sandwiched between the muscular core and the posterior, dorsal epithelium.] 1. epithelium 2. crypts 3. glands B. palatine tonsils D-1 (Fig 13.16; Plate 32) [The tonsil with substantial depth.] 1. epithelium 2. crypts 3. capsule C. pharyngeal tonsil D-3 1. epithelium (you may have to search along the metaplastic strat. squamous ep. to find the remaining pseudostrat. Columnar epithelium characteristic of this tonsil) 2. mucosal folds 3. capsule IV. AGGREGATE NODULES (Figs 13.7; Plate 57, Figs1 & 3; Plate 59) 1. Peyer's patches of ileum E-12, E-13 Fig. 13.17 2. V Appendix E16, E-17 V. Solitary nodules E-12 (Fig 13.14; Plate 74 Fig 2) 1. reticular connective tissue framework 2. lymphocytes 3. germinal center A solitary nodule has to be just that - by itself. So the nodules close together or fused in ileum, tonsils, etc are not solitary. The solitaries will be found in places like the trachea, vagina, u bladder, stomach, where normally there is only a little diffuse Fig 13.13 (but still effective) lymphoid tissue. There is the problem that a cut through the end of a Peyer's patch could yield an image like that of a solitary nodule. Lesson: you should know of them, but they will not appear on the lab exam. VI. DIFFUSE LYMPHATIC TISSUE (lymphatic infiltration): most digestive-tract slides and respiratory-system slides (Figs 13.13 & 18.8; Plates 54, 56, & 58) 1. reticular connective tissue framework 2. lymphocytes For their role, go over Figs. 13.5 through 13.12

HISTOLOGY LAB 20: Neural Tissues II

Neural/nervous tissues are treated again here, and at the end of Human Structure, so as to be close to the Neurobiology Module. All these bolded items, including anything skipped earlier (items VIII though X) could be on the EXAM I. Neurons/nerve cells A. pseudounipolar neurons (Fig. 11.2; Plate 23) 1. spinal (dorsal root) ganglion cells C-2 Before searching for the ganglion cells, examine the slide with the naked eye to make sure that there is a DR ganglion present, in addition to the spinal cord B. multipolar neurons 1. Purkinje cells of cerebellum C-9, C-10 (Plate 26 Fig 2) 2. ventral horn motor neurons of spinal cord C-1, C-2, C-3 (Fig 11.4; Plate 27 Fig 2) 3. Nissl bodies are clumped granular ER Be able to ID in TEM - see Fig 11.5 II. Nerve fibers Plate 24 A. myelinated nerve fibers C-4, C-5, C-6 (Figs. 11.13, 11.10, 11.24; Plate 40) 1. myelin sheath C-4 2. nodes of Ranvier C-5 Fig 11.10b 3. Schwann cells Figs 11.12, 11.16 B. non-myelinated nerve fibers K-11 (Fig. 11.14, 11.19) III. Spinal cord C-1, C-2, C-3 (Fig 11.26; Plate 27; Fig 11.23) A. white matter B. gray matter C. dorsal and ventral horns IV. Ganglia Plate 23 A. sensory ganglia: an example is the spinal/dorsal root ganglion C-2 (Fig 11.17) Find satellite cells around the neuron bodies B. autonomic/motor ganglia 1. sympathetic C-14 (Plate 23 Figs 1 & 27) 2. parasympathetic K-11, E-14 Plate 53 Fig 2; Fig 16.28 AUTONOMIC GANGLION presents an unbalanced ID. One can be sure of a parasympathetic ganglion, if one sees a few (indeed, one) neuron bodies amongst the smooth muscle of a visceral organ's wall. However, to ID a sympathetic ganglion requires high power to recognize the neurons and low power to see that the ganglion is quite large, has its own capsule, and is not part of any other organ. Hence, we will take "autonomic gangion" for parasymp & symp. V. Peripheralnerves (Fig 11.10; Plate 21; Plate 24) C-2, C-4, C-6, K-10, K-11, K-12 A. classification 1. myelinated 2. unmyelinated (a classification needing EM for certainty) Fig 18.21 3. mixed B. Nerve connective tissue coverings 1. endoneurium, recognizable as collagen fibrils in TEM 2. perineurium 3. epineurium (may include large fat cells - black with OsO4) C. Nerve TEM detail Fig 11.10- 11.15, 11-24 1. Axon 2. Myelin lamellae 3. Internal & external mesaxons 4. Schwann cells Fig 11.12 VI Synapses: identify in TEM, and as boutons termineaux C-3, C-14 (Figs 11.5 & 11.7) SYNAPSES C-3 spinal cord. The silver stain shows white-matter axons around the central grey matter where the ventral-horn neurons are yellowish-brown. On the yellow body and start of the dendrites are tiny black structures that sometimes appear as rings with tails. This is as exciting as synapses get. You will encounter their old name "boutons terminaux" from Cajal's publications in French. VII. Motor end-plate in TEM Fig 10.9 1. Prejunctional (axonal) membrane 2. Postjunctional (sarcolemmal) membrane (folded) 3. Vesicles 4. Synaptic Cleft VIII. Sensory receptors (Fig. 14.13; Plate 42) A. Paccinian corpuscle: skin F-4 B. Meissner's corpuscle: skin F-4 XI. Cerebellum Fig. 11.23. Plate 26 1. Purkinje cells 2. Granular layer 3. Molecular layer 4. White matter 5. Folia with pial covering X. Cerebral cortex (cerebrum) Plate 25 1. Pial surface 2. Gray matter of gyrus 3. White matter with mostly oligodendrocyte nuclei 4. Deep gray-matter (layer V has the largest pyramidal neurons See Fig 11.29 and Plate 25 Fig 5, where "Pyramidal cells (PC) are readily recognized", or so is Ross et al.'s questionable claim)

HISTOLOGY LAB 21: Glands and Secretion

As review for theory and lab, by the end of the course you should be able to classify: sweat, gastric, intestinal, Brunner's, sebaceous, pancreas, uterine, salivary, tracheal, mammary, other reproductive glands, & kidney, looking at examples from your slides, and using the ideas at the end of this section. All this material by tradition has been presented early in histology courses on the basis that it belongs with epithelium, since the working/parenchymal cells of glands are epithelial. Our view is that, by all means, give some theory early, but as a lab exercise it should be a late retrospective one I. Classification according to site of release of secretory product A. secretory product released into blood: endocrine secretion B. secretory product released to affect surrounding cells only: paracrine secretion (studied in Physiology) C. secretory product released at epithelial surface, either directly or through a duct: exocrine secretion II. Classification according to number of cells A. unicellular glands 1. goblet cells of respiratory system: trachea G-7 (Fig 18.8; Plate 67 Inset) 2. goblet cells of digestive tract: small intestine E-10 through E-15 (Fig 4.26; Plates 54 through 60) B. multicellular glands (all others listed here) III. Classification according to branching of duct A. simple: duct does not branch 1. glands of stomach lining E-7 & other stomach slides (Fig 4.27) 2. glands of colon lining E-15 (Fig 16.33; Plate 58) 3. sweat glands F-1 (Plates 40 & 41) B. compound: duct branches 1. all salivary glands E-20, E-21, E-22, E-23 (Plates 47-49) 2. pancreas E-24, E-25, E-26 (Plate 64) The term 'simple' applies also to some small glands which do not have a duct. Examples include intraepithelial glands and glands of the colon lining. Compound glands: To ID 1. section may show an actual branching of a duct; 2. many cuts through ducts are to be seen - they would have to come together somewhere; 3. the gland is large, so that only a complicated branching duct system could get the secretion out. IV. Classification according to shape of secretory unit (Table 4.3, p.113) A. tubular 1. straight tubular: glands of colon E-15 2. coiled tubular: sweat glands F-1 B. acinar C. tubulo-acinar: salivary glands E-20, E-21, E-22, E-23 (Note: compare cross section of tubular secretory unit with any section of an acinar secretory unit. Often it will not be possible to distinguish between tubules and acini.) IV. Classification according to method of release of secretion A. holocrine secretion (whole cells are released) 1. sebaceous glands F-3 (Figs 14.14; Plates 38) 2. ovary L-1, L-2 (Fig 22.7; Plate 88) 3. testis K-1, K-2 (Figs 21.5; Plates 82 & 83) B. apocrine secretion (a portion of the cytoplasm may be released with the secretory product) 1. mammary gland L-14 (Fig 22.35) C. merocrine (eccrine) secretion (no cytoplasm released with secretory product) 1. salivary glands E-20, E-21, E-22, E-23 2. all other glands not listed above V. classification according to chemical nature of secretory product A. serous 1. pancreas E-26 Fig 4.29 2. parotid salivary gland E-20 B. mucous 1. goblet cells G-7, E-10 2. stomach lining E-6, E-7 C. mixed (gland includes both serous and mucous secretory units) 1. submandibular salivary gland E-21, E-22 Plate 47 a. serous demilunes 2. sublingual salivary gland E-23 Plate 49 a. serous demilunes D. lipid 1. sebaceous glands: skin F-3 E. glands of special secretion 1. sweat glands: skin F-1, F-3 2. mammary glands L-14 'Mixed' refers to the whole gland, not to individual cells. A mixed gland has some serous and some mucous cells. In the sublingual gland, the serous cells are mostly found in serous demilunes on mucous tubules. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Theoretical background for endocrine and exocrine glands
GLANDS & SECRETIONS: vital for epithelial function and protection, digestion, metabolism, excretion, & control.
Secretions are useful materials made and released by cells. Glands comprise assemblies of secreting epithelial cells. Mesenchymally derived cells secrete many substances - cytokines, prostaglandins, synovial fluid, antibodies, etc., but such cells are not considered to be glandular. Nerve cells also secrete materials, but are viewed in the first instance as neural, not glandular, entities.

Questions for a gland: What is the product(s)? What are its functions? Where is the product released? How much is needed? What is the construction of the gland? Diffuse? Aggregated? Shape? Complexity? How are the gland components controlled? How are epithelia, myoepithelium, smooth muscle, vessels involved? What are the cellular & molecular biologies? Protein & peptide transcription, glycosylation - sites & enzymes, compartment targetting & intracellular traffic, precursor forms & storage, release & destruction mechanisms? Which cell types form tumors? What markers show this?

How far away from the secreting cells does the secretory procduct act or otherwise be useful? And what is the fate of the secreting cell? The notorious CRINE FAMILY spreads its influence via secretions thus: autocrine - leaning on the family at home and on oneself; paracrine - leaning on the neighborhood; endocrine - down the pike to put it to another city. Meanwhile, in the family's exocrine factory (which quite respectably makes laundry detergent) the employee can hand over the product with no injury - merocrine/eccrine secretion; while parting with an arm and a leg - apocrine secretion; or become engorged with the product and die as the way to deliver it - holocrine secretion. [A cytogenic mode produces gametes, although 'holocrine' is also applied to gamete formation.]

DETERMINANTS OF GLAND STRUCTURE - What sort of secretion; how much is needed; & where it is to be released & used. Hormones are potent & little is needed, are used at a distance, & need not be modified in a duct. Therefore, to construct an endocrine gland, clumps or cords of epithelial cells face wide capillaries with leaky or fenestrated endothelium on a support of reticular fibers. If intracellular storage is not enough, follicles form, e.g. in thyroid, parathyroid, and pituitary glands. Epithelial cytology reflects the hormone's chemistry: variables being granule size & density, ER, lysosomes, PAS reactivity (indicating glycoproteins), etc.

EXOCRINE GLANDULAR TYPES based firstly on morphology, secondly on the product(s) 1 Diffuse 'unicellular' gland - mucus-secreting goblet cells in an epithelium 2 Secretory sheet - all surface cells secrete mucus, e.g., stomach lining 3 For concentration on the job of secretion, to reduce bulk, & to let the lining epithelium get on with its work, exocrine glands become separated from, but attached by a duct to, an epithelium.

Simple: a single or no duct; Compound - branching duct system (& gland is usually large) Each of these major classes is subdivided according to the shape(s) of the secretory units: simple straight tubule, simple coiled tubule, simple branched tubule, & simple acinar/alveolar versus compound tubular, compound acinar, & compound tubulo-acinar/alveolar. Alveoli can be greatly dilated, e.g. active breast, prostate, or have a lumen barely visible in LM. 4 Product classes - Serous cells produce and store proteins; mucous cells make bulk glycoproteins (mucins), which often push the nucleus to the base of the cell. (Many so-called serous cells include glycoproteins among their products, thus certain salivary glands have mucous tubules with crescents of serous (seromucous) cells capping the ends.) Another product is lipid, but few cells make only lipids.

DUCT TERMS are based on position and function, which overlap but do not coincide exactly. Within a lobule are intralobular and intercalated ducts, & the intralobular duct may or may not be secretory (actively altering the secretion). Interlobular and interlobar ducts are usually excretory. Secretory duct cells possess basal infoldings, some microvilli, & many mitochondria (whose enzymes stain red with eosin) for pumping ions to specify electrolyte composition and water content.


HISTOLOGY LAB: Slide List

Section A: Cytology and miscellaneous A-1 Blood smear Wright's stain A-2 Bone marrow smear Wright-Giemsa A-3 Mitochondria, liver iron hematoxylin A-4 Golgi in trigeminal ganglion DaFano A-5 Mesothelial spread silver nitrate A-6 Tendon, xs & ls H&E A-7 Adipose: rabbit mesentery H&E A-8 Connective tissue spread H&E A-9 Connective tissue spread aldehyde fuchsin A-10 Connective tissuue spread H&E A-11 Elastic cartilage, dog ear elastic A-12 Elastic cartilage, dog ear H&E A-13 Intervertebral disc H&E A-14 Pubic symphysis H&E A-15 Bone, human dry ground A-16 Developing long bone H&E A-17 Developing phalanges H&E A-18 Long bone H&E A-19 Fetal face, human H&E A-20 Fetal finger H&E A-21 Humerus, 1 day kitten H&E A-22 Muscle: 3 types H&E A-23 Skeletal muscle, human trichrome -------------------------------------------------------------------------- Section B: Cardiovascular system B-1 Aorta, human H&E B-2 Aorta, human Mallory's B-3 Aorta, human elastic B-4 Vena cava, human H&E B-5 Vena cava, human elastic B-6 Heart, human H&E B-7 Heart valve, human H&E B-8 Heart, Purkinje fibers Mallory's B-9 Artery & vein H&E -------------------------------------------------------------------------- Section C: Nervous tissue C-1 Spinal cord, human H&E C-2 Spinal cord & ganglion H&E C-3 Spinal cord: boutons silver C-4 Myelinated nerve osmium C-5 Teased nerve osmium C-6 Peripheral nerve H&E C-7 Cerebral cortex H&E C-8 Cerebral cortex silver C-9 Cerebellum H&E C-10 Cerebellum silver C-11 Eye, human fetus H&E C-12 Eye, median section H&E C-13 Inner ear, guinea pig H&E C-14 Sympathetic ganglion silver -------------------------------------------------------------------------- Section D: Lymphatic tissues D-1 Palatine tonsil, human H&E D-2 Lingual tonsil, monkey H&E D-3 Pharyngeal tonsil, human H&E D-4 Lymph node, plastic H&E D-5 Lymph node, human H&E D-6 Lymph node, human silver D-7 Lymph node with carbon H&E D-8 Spleen, dog H&E D-9 Spleen, monkey H&E D-10 Spleen, human H&E D-11 Spleen, dog H&E D-12 Thymus, young & adult H&E -------------------------------------------------------------------------- Section E: Digestive system E-1 Esophagus, upper H&E E-2 Esophagus, middle H&E E-3 Esophagus, lower H&E E-4 Cardio-esophageal juntction H&E E-5 Stomach, cardiac, monkey H&E E-6 Stomach, fundic, monkey H&E E-7 Stomach, fundic, human H&E E-8 Stomach, pyloric, monkey H&E E-9 Pyloro-duodenal junction H&E E-10 Duodenum H&E E-11 Jejunum H&E E-12 Ileum H&E E-13 Ileum H&E E-14 Colon, monkey H&E E-15 Colon, human H&E E-16 Appendix, young H&E E-17 Appendix, old H&E E-18 Recto-anal junction H&E E-19 Anal canal H&E E-20 Parotid gland, human H&E E-21 Submandibular, human H&E E-22 Submandibular, monkey H&E E-23 Sublingual, human H&E E-24 Pancreas, human trichrome E-25 Pancreas chrome alum E-26 Pancreas H&E E-27 Liver, pig H&E E-28 Liver, pig trichrome E-29 Liver, human H&E E-30 Liver, human trichrome E-31 Liver, human silver E-32 Liver, glycogen Best's carmine E-33 Gall bladder, human H&E E-34 Gall bladder, monkey H&E -------------------------------------------------------------------------- Section F: Integument F-1 Thick skin H&E F-2 Thin skin H&E F-3 Scalp and hair H&E F-4 Pacinian corpuscles H&E F-5 Fingernail H&E F-6 Eyelid H&E F-7 Lacrimal gland H&E -------------------------------------------------------------------------- Section G: Respiratory system G-1 Nasal cavity, kitten H&E G-2 Epiglottis H&E G-3 Epiglottis elastic G-4 Larynx H&E G-5 Trachea, human H&E G-6 Trachea, human elastic G-7 Trachea, monkey H&E G-8 Lung, fetal, human H&E G-9 Lung, human H&E G-10 Lung, normal & coal dust H&E G-11 Lung, monkey H&E G-12 Lung & bronchus H&E (even #ed sets only) -------------------------------------------------------------------------- Section H: Urinary system H-1 Kidney, human H&E H-2 Kidney, human H&E H-3 Kidney, human PAS H-4 Ureter, human H&E H-5 Ureter, monkey H&E H-6 Urinary bladder, monkey H&E H-7 Urinary bladder, monkey H&E -------------------------------------------------------------------------- Section J: Endocrine organs J-1 Hypophysis, human H&E J-2 Hypophysis, human trichrome J-3 Hypophysis, human PAS J-4 J-5 Thyroid, human H&E J-6 Thyroid, human silver J-7 Parathyroid, human H&E J-8 Adrenal, monkey H&E -------------------------------------------------------------------------- Section K: Male reproductive system K-1 Testis, human H&E K-2 Testis, monkey H&E K-3 Testis & epididymis, dog H&E K-4 Sperm smear, human iron hematoxylin K-5 Rete testis, human H&E K-6 Efferent ducts H&E K-7 Epididymis, human iron hematoxylin K-8 Ductus deferens, human H&E K-9 Ductus deferens, monkey H&E K-10 Seminal vesicle, human H&E K-11 Seminal vesicle, human H&E K-12 Seminal vesicle, monkey H&E K-13 Prostate, human H&E K-14 Prostate, human trichrome K-15 Penis, human H&E K-16 Penis, human H&E -------------------------------------------------------------------------- Section L: Female reproductive system L-1 Ovary, human H&E L-2 Ovary, monkey H&E L-3 Corpora lutea, dog H&E L-4 Oviduct, ampulla, human H&E L-5 Oviduct, isthmus, human H&E L-6 Uterus, proliferative H&E L-7 Uterus, secretory H&E L-8 Uterus, menstrual H&E L-9 Uterus, monkey H&E L-10 Cervix, human H&E L-11 Vagina, human H&E L-12 Vagina, human Best's Carmine L-13 Mammary gland, pregnant H&E L-14 Mammary gland, active H&E L-15 Placenta H&E L-16 Umbilical cord H&E -------------------------------------------------------------------------- Section M: Oral histology M-1 Lip H&E M-2 Cheek H&E M-3 Tongue, x.s H&E M-4 Tongue, circumvallate H&E M-5 Tongue, fungiform H&E M-6 Tooth, long. section dry ground M-7 Tooth, crown, x.s. dry ground M-8 Tooth, root, x.s. dry ground M-9 Early tooth formation, pig H&E M-10 Later tooth formation, pig H&E M-11 Tooth formation, human H&E M-12 Lip & dev. tooth, human H&E M-13 Mand. dev. tooth, human H&E M-14 Mandible, l.s., dog silver M-15 Incisor, l.s., dog H&E M-16 Mandible, horiz. sect., dog H&E M-17 Mand/molar roots, monkey silver M-18 Mand/molar roots, monkey trichrome M-19 Mandible & molar, monkey H&E M-20 Mandible & molar, monkey H&E M-22 Mandib. condyle, monkey H&E M-23 Articular disc, human H&E