1. Types of Epithelia A pictorial essay
histology
Types of Epithelia
A pictorial essay

2. Epithelial Terms Simple: one layer thick
Stratified: more than one layer thick, obvious by linear arrangement of stained nuclei
Pseudo-Stratified: looks like more than one layer thick, but is actually only one layer thick.
Transitional: like a super pseudo-stratified layer it is used for epithelial tissue that expands and contracts many times (like bladders, etc.)

3. Epithelial cell types
Squamous
Cuboidal
Columnar

4. Simple squamous epithelium
Squamous epithelium has that “dinner plate” look (thin on edge, roundish from the top.

5. Simple Squamous Cont’d
Locations
lining of ventral body cavities
lining of heart and blood vessels
lining of portions of kidney tubules
cornea of eye, and alveoli of lungs
Functions
reduce friction
control permeability
perform absorption and secretion functions

6. Stratified squamous epithelium
Layers of Squamous cells on the apical side with layers of stem cells on the basal side.

7. Stratified squamous cont’d
Location
surface of skin
lining of mouth, throat, esophagus, rectum, anus and vagina
Function
provide physical protection against abrasion, pathogens, and chemicals

8. Simple cuboidal epithelium
Cells shaped like cubes, with very large nuclei

9. Simple cuboidal cont’d
Location
glands, ducts, portions of kidney tubules, thyroid gland
Function
Limited protection, secretion and/or absorption

10. Stratified cuboidal epithelium
Same cells as simple, just several layers

11. Stratified cuboidal cont’d
Location
lining of some ducts (rare)
Function
protection
secretion
absorption

12. Simple columnar epithelium
The cells are column shaped and generally have the nucleus in the lower half.

13. Simple columnar cont’d

14. Simple columnar cont’d
Location
lining of stomach, intestine, gallbladder, uterine tubes, collecting ducts of kidney
Function
protection
secretion
absorption

15. Pseudostratified columnar epithelium
Columnar cells whose nuclei fool you into thinking they are stratified.

16. Pseudostratified columnar cont’d
This one is ciliated and pseudostratified

17. Pesudostratified columnar cont’d
Location
trachea
lining of nasal cavity, bronchi
Function
protection
secretion
mucous transport

18. Stratified columnar epithelium
Stacked columnar cells

19. Stratified Columnar Cont’d

20. Stratified columnar Cont’d
Location
salavary gland duct
small areas of pharynx, epiglottis, anus, mammary ducts, and urethra
Function
protection

21. Transitional epitheilum
Look carefully at the cells, they appear different shapes and bunched up.

22. Transitional cont’d Location Function urinary bladder renal pelvis
ureters
Function
permit expansion and recoil after stretching

23. Test yourself
What type of epithelial tissue is this ?

24. The answer If you guessed:
Ciliated Pseudostratified Columnar Epithelium
You were RIGHT !, Congratulations

25. End of show The Attack of the Ancient Connective Tissue
Stay tuned for our next exciting episode:
The Attack of the Ancient Connective Tissue