This document reviews different types of epithelial tissues found in the body. Simple squamous epithelium lines structures like the kidney's Bowman's capsule and arteries. Simple cuboidal epithelium forms the lining of renal tubules and collecting ducts in the kidney. Simple columnar epithelium is seen in the gallbladder, duodenum, and other organs. Ciliated pseudostratified columnar epithelium lines the respiratory tract while stratified squamous epithelium has many layers, as seen in the esophagus and skin. Transitional epithelium, with a variable number of cell layers, is found in the ureters and urinary bladder.

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2. SSiimmppllee ssqquuaammoouuss eeppiitthheelliiuumm
Kidney – median sagittal section – H&E – 10x objective
Arrowheads indicate the locations of Bowman’s capsules within the cortex of
the kidney. This is one place to locate simple squamous epithelium.

3. SSiimmppllee ssqquuaammoouuss eeppiitthheelliiuumm
Kidney – median sagittal section – H&E – 40x objective
Bowman’s capsule
lumen
Single layer of flattened cells with prominent flattened nucleus, very thin, lining
the capsular space of Bowman’s capsule

4. SSiimmppllee ssqquuaammoouuss eeppiitthheelliiuumm
Artery – cross section – H&E – 40x objective
lumen
Flattened cells, one cell layer thick, lining the lumen of an artery

5. SSiimmppllee ccuubbooiiddaall eeppiitthheelliiuumm
Kidney – median sagittal section – H&E – 10x objective
Arrowheads indicate renal tubules in the kidney cortex. “Tubule” is a key word,
telling you this is one place to locate simple cuboidal epithelium.

6. SSiimmppllee ccuubbooiiddaall eeppiitthheelliiuumm
Kidney – median sagittal section – H&E – 40x objective
lumen
lumen
Approximate location of
basement membrane
Approximate size of one cell
Renal tubules (arrowheads) – note that the cells appear about as tall as they
are wide and that there is a single layer of cells.

7. SSiimmppllee ccuubbooiiddaall eeppiitthheelliiuumm
Kidney – median sagittal section – H&E – 40x objective
lumen
In the renal medulla you find collecting ducts, lined with a single layer of simple
cuboidal cells.

8. SSiimmppllee ccuubbooiiddaall eeppiitthheelliiuumm
Thyroid gland – cross section – H&E – 40x objective
lumen
lumen
Simple cuboidal epithelium (arrowheads) forms follicles in the thyroid gland.

9. SSiimmppllee ccuubbooiiddaall eeppiitthheelliiuumm
Pancreas – section – H&E – 40x objective
lumen
Duct (arrowhead indicates location of the basement membrane) within the
pancreas. Note the single layer of simple cuboidal cells.

10. SSiimmppllee ccoolluummnnaarr eeppiitthheelliiuumm
Gallbladder – section – H&E – 10x objective
lumen
Villi (arrowheads) – finger-like processes inside the gallbladder. This organ of
the digestive system is line with simple columnar epithelium.

11. SSiimmppllee ccoolluummnnaarr eeppiitthheelliiuumm
Gallbladder – section – H&E – 40x objective
Basement membrane would
be located along this line.
Approximate size of one cell
lumen
Note that the simple cuboidal cells are taller than they are wide.

12. SSiimmppllee ccoolluummnnaarr eeppiitthheelliiuumm
Duodenum – section – H&E – 40x objective
Basement membrane would
be located along this line.
Approximate size of one cell
lumen
Although this looks different from the gallbladder, this is still simple columnar
epithelium.

13. CCiilliiaatteedd ppsseeuuddoossttrraattiiffiieedd ccoolluummnnaarr eeppiitthheelliiuumm
Trachea – cross section – H&E – 10x objective
lumen
Basement membrane would
be located along this line.
epithelium
Underlying connective tissue
This is the signature epithelium of the respiratory system. Note the difference
between epithelium above and connective tissue below the line.

14. CCiilliiaatteedd ppsseeuuddoossttrraattiiffiieedd ccoolluummnnaarr eeppiitthheelliiuumm
Trachea – section – H&E – 40x objective lumen
cilia
Basement membrane
All cells contact the basement membrane, but not all cells reach the surface. It
only appears stratified, hence the name.

15. CCiilliiaatteedd ppsseeuuddoossttrraattiiffiieedd ccoolluummnnaarr eeppiitthheelliiuumm
Intrapulmonary bronchus – section – H&E – 40x objective
lumen
cilia
Basement membrane
You can tell this isn’t stratified columnar epithelium because no can’t discern
individual layers. Stratified columnar would have clear rows of nuclei.

16. SSttrraattiiffiieedd ssqquuaammoouuss eeppiitthheelliiuumm
Esophagus – section – H&E – 10x objective lumen
Basement membrane
How many layers of
cells do you see here?
Underlying connective tissue
It is easy to see why this is called a stratified epithelium. I counted about 35
layers of cells stretching from the basement membrane to the apical surface.

17. (nonkeratinized) Stratified ssqquuaammoouuss eeppiitthheelliiuumm
Esophagus – section – H&E – 20x objective lumen
Basement membrane
Cells at the basal surface are cuboidal and mitotic. As new cells are pushed to
the top, they become increasingly squamous in shape.

18. Keratinized stratified ssqquuaammoouuss eeppiitthheelliiuumm
Human skin – section – H&E – 10x objective
free surface
Basement membrane
Keratinized layers of cells
Again, look at the layers of cells between the basement membrane and the
apical surface.

19. Keratinized stratified ssqquuaammoouuss eeppiitthheelliiuumm
Human skin – section – H&E – 40x objective
Keratinized layers of cells – very
long, thin and flattened (scale-like)
Free surface
Basal surface
Epithelium
Cuboidal cells at the basal surface give way to increasingly flattened cells
(squamous) in the upper layers. The cells are filled with water-proof keratin.

20. SSttrraattiiffiieedd ccuubbooiiddaall eeppiitthheelliiuumm
Submandibular (salivary) gland – section – H&E – 40x objective
Basal layer of cells
Approximate size of one apical cell
Apical layer of cells
lumen
Larger ducts of the body may have a stratified cuboidal epithelium, where the
top layer of cells is cuboidal. There are usually only two layers of cells.

21. SSttrraattiiffiieedd ccoolluummnnaarr eeppiitthheelliiuumm
Submandibular (salivary) gland – section – H&E – 40x objective
Apical layer of cells
Approximate size of
one apical cell
lumen
Basal layer of cells
What is the epithelial type?
Very large ducts of the body may have a stratified columnar epithelium, where
the top layer of cells is columnar. There are usually only two layers of cells.

22. TTrraannssiittiioonnaall eeppiitthheelliiuumm
Ureter – cross section – H&E – 10x objective
Epithelial layer
lumen
Basal layer of cells
Underlying connective
tissue layer
Transitional epithelium is the signature epithelium of the urinary tract. It is
found in the ureters and urinary bladder.

23. TTrraannssiittiioonnaall eeppiitthheelliiuumm
Ureter – cross section – H&E – 40x objective
lumen Apical layer of cells
Basal layer of cells
When the organ walls are under low
tension, the epithelium has 6 – 8
layers of cells.
This is called transitional epithelium because the number of cell layers changes
as the organ walls increase and decrease in tension.

24. TTrraannssiittiioonnaall eeppiitthheelliiuumm
Urinary bladder – section – H&E – 10x objective
lumen
Basement membrane
The urinary bladder looks different from the ureter because it is a different
organ with different function, but the epithelium is still transitional.

25. TTrraannssiittiioonnaall eeppiitthheelliiuumm
Urinary bladder – section – H&E – 40x objective
Apical layer of cells
lumen
Basal layer of cells
Basement membrane
The distinguishing features of this epithelium are multiple layers and the very
large “sofa pillow-like” cells at the apical surface.
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