Objectives:

1. Tall pseudostratified columnar epithelium with numerous layers of nuclei. Three cell types present

a. Olfactory cells

1. Nuclei form most of the intermediate layers
2. Non-motile cilia extend into the lumen of the epithelium

b. Sustentacular cells

a. Bowmans's glands

The slide of this epithelium is well worth looking at. The picture shown above corresponds to a small number of slides. However, it should serve to help most of you with the other slide to find the particular features in your slide. The preservation is excellent and the slide contains pieces of the respiratory epithelium to compare with the olfactory segment. Pay particular attention to the olfactory nerves. These are unusual in that the Schwann cells have an almost cuboidal shape and are tightly packed within the nerve fiber bundle. The nerve fibers are non-myelinated and so the individual fibers cannot be distinguished. However, up to 50 nerve fibers can be ensheathed by a single Schwann cell. Contrast the olfactory epithelium with the respiratory segment which is ciliated and visible in the same slide.

 
B. Epiglottis See plate 14 on page 147

The large number of epiglottis slides in this laboratory exercise belies the importance of this organ. It is not essential to swallowing. However, the slides do reveal several interesting features. One is the presence of metaplastic changes in the epithelium from stratified squamous to pseudostratified columnar. The other is the replacement of elastic cartilage with adipose tissue. It is not necessary to spend too much time viewing this organ.
1. Thin foliate lamella of elastic cartilage covered by a non-keratinized stratified squamous epithelium.
2. Seromucous glands are frequent overlying the cartilage.

 
121B Epiglottis, l.s.

This slide has several unusual features that are worth noting.

First, the epiglottis characteristically consists of a epithelium, an underlying lamina propria and a layer of elastic cartilage (check plate 14 on page 147). The epithelium is stratified squamous, non-keratinized. The elastic cartilage can be partially replaced by adipose tissue and that is what has apparently happened here except that the cartilage has been mostly replaced. However, there is enough of the cartilage structure remaining for you to perhaps find some islands of chondrocytes and the remnants of a perichondrium.

Second, epithelium changes occur where the lymphatic follicles are located (there were two nodules in the slide I examined). Here the epithelium changes from stratified squamous to pseudostratified columnar with ciliated cells. This is an example of metaplasia (see page 535 of R,R,&K). Note that a piece of hyaline cartilage and seromucous glands can also be found in the tissue.

121C Epiglottis, Masson, human

This slide is just like 121a except stained with Masson stain which enhances the connective tissue. Some slides contain stratified columnar ducts associated with the seromucous glands. Metaplastic epithelium changes can also be found but they are not always obviously associated with nodules. Note the orange color of the fibers in the cartilage.
 

  C. Trachea

1. Pseudostratified, ciliated columnar epithelium
2. Goblet cells (mucous secreting)
3. Basal cells
4. Brush cells (MV)
5. Dense granule (APUD)
6. Intermediate cells
7. Serous cells (found in glands)
8. Submucosal glands (sero-mucous) with cuboidal ducts leading directly to surface
9. Cartilaginous rings (hyaline)
10. Membranous wall: smooth muscle, connects ends of cartilaginous rings

This slide was examined in the earlier epithelium lab. It shows the trachea in longitudinal section. The structure consists of overlapping cartilage rings, submucosal glands and a pseudostratified columnar epitheium with ciliated cells and goblet cells. Some simple columnar ducts can be found in the groups of seromucous glands.

120 Trachea & esophagus, c.s. 
This slide shows the trachea in cross section. The cartilage appears as a "C" shaped ring with the opening spanned by a bundle of smooth muscle fibers. Submucosal glands are not as common as in a longitudinal section but can be found. In the epithelium, goblet cells are difficult to find because the section is thick. Probably the goblet cells are the ones with the elongated nuclei that are just next of the basal layer. The ciliated cell nuclei are closer to the lumen, whereas the basal cell nuclei are just that, on the base of the epithelium.
 

120A Trachea & Esophagus, H&E
This slide contains both trachea and esophagus, which run in parallel in the mediastinum. Some slides have a small piece of thymus attached, an organ that is also found in this region. The epithelium consists of several apparent cell layers (not just two) but the outer most layer looks columnar. This appearance is characteristic of pseudostratified columnar which often shows nuclei at more than two levels. The surface has many cilia. The C-clip of hyaline cartilage dominates the trachea portion. The two free ends are connected by the trachealis muscle, which is a smooth muscle. Some slides may show submucosal glands in the trachea. The muscularis of the esophagus is typical of upper regions of the organ. It consists of skeletal muscle in two orientations, the longitudinal shows striations. The thick muscularis mucosa consists of smooth muscle. The epithelium of the esophagus is non-keratinized stratified squamous.

 
D. Lung
Bronchi

115B Lung, human

For observing bronchi and bronchioli this slide is not as good as 115a.  However, it gives a better impression of the distribution of capillaries and alveolar Type I cells in the alveoli. Endothelial cells can be seen in the capillaries whereas between the capillaries in the alveolar septum is a rounder nucleus with very little apparent cytoplasm attached to it. This is the Type I cell. A visceral pleura lines part of the tissue surface.

 
115C Lung periph. monkey, H&E
This slide is a bit strange. There is a lot of large vasculature but very little in the way of conducting airways. Some alveoli are badly distended, others are collapsed. Associated with the largest vessels are some very large openings which seem artifactual. The only thing that I am comfortable identifying is the visceral pleura which covers nearly all sides of this tissue.

116A Lung, monkey, Mallory
116B Lung, monkey, H&E 
These 2 companion slides, one stained with H&E, the other with Mallory, contains secondary bronchi and smaller branches of the airways. The connective tissue capsule and its mesothelium are intact. The bronchi can be identified by the cartilage, which in some cases is accompanied by submucosal glands. Mallory stains the connective tissue blue, nuclei red, RBCs are red. The Mallory stain is a bit too intense thereby blocking recognition of cell types. The preservation of the ciliated cells is poor. You will have to hunt for small purely conducting passageways but there are both conducting and respiratory bronchioles present.

 Lung, rabbit, 1.5µm, BF-TB
This is a 1.5µm thick plastic section stained with basic fuschin and methylene blue. The alveoli are distended making it relatively easy to identify the thin capillary walls where gas exchange occurs. Examine some of these at 40x to observe some which have endothelial cell nuclei within them. Alveolar type I cells are the nuclei that are adjacent to the capillaries. Capillaries in the alveoli are mostly free of blood, but the larger vessels are not. Alveolar Type II cells have a foamy appearance with clear granules in their cytoplasm. Alveolar macrophages are the large cells that seem to be free standing in the alveoli. Other cell types are not easily distinguished. Each slide has a bronchus which is identifiable by the presence of cartilage and a large muscular artery adjacent to it. Most of the cells lining the lumen of the bronchus are ciliated cells. Goblet cells are not apparent. The brownish-red substance is collagen. Underlying the bronchial epithelium is a layer of smooth muscle, identifiable by its blue appearance. The muscular artery is cut in oblique section so that the t. intima appears unusually large. You can identify an internal and external elastic lamina clearly. This slide seems to be essentially free of bronchioles.

E. Larynx and vocal cord.
This slide can be treated as an optional slide.

 
 Larynx & vocal cord, Monkey

This tissue seems to contain both the vocal cord and the ventral fold. The vocal cord is identifiable as the flap of tissue bounded by a stratified squamous epithelium. Adjacent to it is a large block of skeletal muscle, the vocalis. Large blocks of cartilage are also present. The epithelium is not well preserved everywhere, but around the ventral fold it is apparently stratified columnar or pseudostratified columnar epithelium. Note the presence of many seromucous glands.

A. Kidney
1. Cortex/Medulla organization

a. Cortex contains renal corpuscles/Juxtaglomerular apparatus/proximal & distal convoluted tubules/cortical collecting ducts
b. Medulla contains loops of Henle/medullary pyramids/calyces/renal papilla

a. Glomeruli surrounded by Bowman's capsule/urinary space
b. Tend to be in parallel rows to capsule (run along interlobular arteries)
c. Afferent/Efferent arterioles
d. Cells include endothelial (capillaries), mesangial, and podocytes
e. Juxtaglomerular apparatus

1. Prominent nucleus (cells differentiate from smooth muscle)
2. Macula densa (modified DCT, taller and more prominent nuclei, 6-10 closely packed)
3. Lacis cells (between macula densa and Bowman's capsule)

a. Proximal convoluted tubule (PCT)

122A Kidney, Masson, human 

Proximal convoluted tubules are the darker stained tubules with irregularly spaced nuclei and a large diameter. The brush border is not preserved. Distal convoluted tubules are have more regularly stained nuclei, smaller diameter and paler stain. Medullary rays penetrate the cortex. These rays contain collecting tubules and ascending and decending thick limbs, mostly they consist of thick limbs. These limbs resemble the proximal and distal convoluted tubules that they are associated with, except that they are straight..

The medulla is divided into three regions. The outer and inner stripes of theouter medulla and the inner medulla. The inner medulla is the easiest to navigate because it consists of essentially collecting tubules, Henle’s thin limb and vasa recta. Erythrocytes stain a greenish brown. Henle’s thin limb can be distinguished from vasa recta by the absence of erythrocytes. The collecting tubules havae shrunk and separated from their basal lamina. They are darkly stained however and are the only darkly stained tubules in the inner medulla. Arcuate arteries and veins are the large vessels at the boundary of cortex and medulla.

122C Kidney sec.

This slide has less blood in it and so it will be more difficult to distinguish thin limbs from vasa recta. That said, the preservation is quite nice for kidney. You will note that there are apparently few distal convoluted tubules. They are generally fewer than theproximal but this tissue has many fewer than expected. There is a pretty good CT capsule associated with this tissue. Medullary rays are difficult to see.

122B Kidney, human
This slide has not been perfused so the capillaries contain RBCs. The tissue does not contain much of the entire range of tissues, but does contain a small bit of inner medulla. Medullary rays are very prominent. In this slide the association of vasa recta with the thin limbs is quite proinent because the inner medulla has beencut in cross section. Look for islands of red, which reveal the vasa recta clusters. At higher magnification, you will see small tubules with a squamous epithelium. These are the thin limbs. In addition, you will see other regions consisting of nearly uniform collecting tubules with some capillaries associated with them.

123 Kidney, median sag. sec
If you can study only one kidney slide, study this one. It is a sagital section through a unilobar kidney of a small mammal. It shows the calyx, papilla and some transitional epithelium of the renal pelvis. The tissue has not been perfused so that RBCs are found in the capillaries.

 
124B Kidney, rabbit, PAS&H RR&K Fig. 1.2 (page 6), Plates 93-96 (page 585-591)
124C Kidney; rabbit, Masson

You looked at this slide in the epithelium lab. Now go back to it and see if you can find and identify the different structures.
 
B. Ureter

125B Ureter, M.A., human

This is another typical cross section of ureter stained with Mallory-Azan to highlight connective tissue. A large artery and vein are associated with this tissue. The surface layer of cells in the epithelium has exfoliated but some intact regions remain. Smooth muscle bundles in the muscularis are cut in cross section in the inner layer and longitudinal section in the outer layer.

125C Ureter, primate, c.s., H&E
This slide of ureter has some extra cells in the center of the lumen. This is not an artifact (see plate 97). Note that the inner layer of smooth muscle (plainly visible) is cut in cross section. There is a small amount of a 3rd muscle layer cut in cross section. What does this signify? The transitional epithelium is well preserved.
 

C. Bladder

1. Transitional epithelium

127B Urinary bladder, collapsed, human
This slide reveals a highly folded transitional epithelium characteristic of urinary tract. The muscularis contains large bundes of smooth muscle in at least two orientations. An adventitia lies outside the muscularis. Urinary bladder is surrounded with an adventitia over most of its surface except at the top which lies just below the abdominal peritoneum cavity. The epitheium has suffered some exfoliation of the surface cells.

127A Urinary bladder, Masson
This slide shows a distended bladder mucosa. The epithelium is degraded but still retains characteristics of transitional structure. Two clear layers of smooth muscle lie underneath the epithelium and submucosa.

 

Respiratory nasal cavities  vestibule  respiratory segment  olfactory segment  olfactory mucosa  Bowman’s glands  ofactory epithelium  olfactory cells  sustentacular cells  basal cells  brush cells nasal septur  turbinates/conchae  turbulent precipitation nasopharynx  pharyngeal tonsil  oropharynx  larynx  vocal folds/cords  glottis  vocalis muscle  ventricular folds  false vocal cords trachea  trachealis muscle  elastic membrane respiratory epithelium  ciliated cells  goblet cells  brush cells  small granule cells  basal cells bronchi  primary/extrapulmonary  intrapulmonary  lobar /secondary  segmental/tertiary bronchioles  pulmonary lobules  pumonary acini  conducting bronchiole  respiratory bronchiole  terminal bronchiole  Clara cells cystic fibrosis  alveolar ducts  alveolar sacs  alveoli  aveolar septum  Type I cells  Type II cells  septal cells  surfactant  lamellar bodies  air-blood barrier  thin portion  thick portion  alveolar macrophages pores of Kohn pulmonary circulation  bronchial circulation

Kidneys  hilum  cortex/medulla  renal pelvis  renal sinus  nephron  pyramids  papilla  minor calyx  major calyx  area cribrosa  lobe  collecting tubules  medullary rays  uriniferous tubule  cortical labyrinths  countercurrent exchange  renal columns  proximal thick segment  proximal convoluted tubule/pars convoluta proximal straight segment/pars recta thin segment  loop of Henle  distal thick segment  distal convoluted tubule/pars convoluta  distal straight segment/pars recta cortical/subcapsular nephrons  juxtamedullary nephrons  intermediate nephrons  cortical collecting ducts  ducts of Bellini  medullary rays  renal corpuscles  macula densa  glomerulus  Bowman’s capsule  vascular pole  urinary pole  renal/malphigian corpuscles  semipermeable barrier  podocytes  pedicels/foot processes  filtration slits  filtration slit membrane  glomerular basement membrane  mesangium/mesangial cells  parietal layer  juxtaglomerular apparatus  juxtaglomerular cells  kidney hormones  erythropoietin  renin  vitamine D  renin  angiotensis I/II  aldosterone  antidiuretic hormone ADH) vascular network  renal artery  interlobar branches  arcuate artery  interlobular arteries  afferent arteriole  efferent arteriole  vasa recta  peritubular capillary network  transitional epithelium  plaques Ureter  Bladder  internal sphincter Urethra  prostatic urethra  membranous urethra  penile urethra  glans penis