This document provides information about epithelium: - Epithelium is a primary tissue that covers body surfaces, lines cavities, and forms glands. It develops from all three germ layers and has chief characters of being predominantly cellular, having adhesion, and a basement membrane. - Epithelium is classified as unilaminar (simple) or multilaminar (stratified). It performs important functions like secretion, absorption, transportation, protection, sensation, and lubrication. Examples of different epithelial tissues are provided.

1. EPITHELIUM
Maj Rishi Pokhrel
Dept of anatomy
NAIHS
www.slideshare.net

2. Histology?
• Microscopic anatomy?

3. At the end of this class you should be able to ..
• Define epithelium
• Classify epithelium with examples
• Correlate epithelium with their function

4. INTRODUCTION
• Primary tissue
• Epi - Upon, Thelia - Projection, Nipple
PAPILLA/ PROJECTION

5. DEFINITION: layer (s) of cells that covers body surfaces,
lines body cavities or constitute glands

6. DEVELOPMENT
• From all three germ layers
• Ectoderm - skin, mouth, nose, anal canal
• Endoderm - GIT, glands, resp tract, distal parts
of GU tract
• Mesoderm - body cavities, endothelium,
proximal parts of GU tract

7. CHIEF CHARACTERS
• Predominantly cellular
• Adhesion
• Basement membrane
» Basal lamina
» Reticular lamina
• Avascular
• Cell shape
• Regeneration - tumors common

8. FUNCTIONS
•Secretion- columnar epithelium of stomach and gastric
gland
•Absorption- columnar epithelium in intestine and PCT
in kidney
•Transportation- material of cells along the surface of
epithelium by motile cilia
•Protection- skin and urothelium in bladder
•Receptor- taste and olfaction
•Lubrication

9. CLASSIFICATION
EPITHELIUM
UNILAMINAR
(SIMPLE)
MULTILAMINAR
(STRATIFIED)
SQUAMOUS
COLUMNAR
CUBOIDAL
STR SQUAMOUS
STR COLUMNAR
STR CUBOIDAL
TRANSITIONAL
PSEUDOSTRATIFIED
Specialization

12. Simple squamous epithelium
•A single layer of flattened cell ( “pavement”) disc shaped central nuclei
•Thin cytoplasm

13. SIMPLE CUBOIDAL EPITHELIUM

14. SIMPLE COLUMNAR EPITELIUM

15. COLUMNAR EPITHELIUM WITH MICROVILLI
Gall bladder

16. CILIATED COLOUMNAR EPITHELIUM
Brush border

17. CILIATED COLOUMNAR EPITHELIUM

18. GOBLET CELL

19. PSEUDOSTRATIFIED
COLUMNAR
NON-CILIATED
PSEUDOSTRATIFIED
COLUMNAR CILIATED

20. PSEUDOSTRATIFIED COLUMNAR WITH
STEREOCILIA
Epididymis

21. STR SQUAMOUS NON KER EPITHELIUM

22. STR SQUAMOUS KER EPITHELIUM

23. STR CUBOIDAL EPITHELIUM

24. STR CUBOIDAL EPITHELIUM

25. STRATIFIED COLUMNAR

26. TRANSITIONAL EPITHELIUM

27. TRANSITIONAL EPITHELIUM

28. Assignment
• Cell junctions??

30. ?

31. CONTACTS BETWEEN ADJOINING
CELLS
CLASSIFICATN OF CELL CONTACTS
1. UNSPECIALISED CONTACTS
2. SPECIALISED JUNCTIONAL STRS
A. Occluding jns or Zonula occludens or
tight jns
B. Anchoring jns or Adhesive jns
• Adhesive belts or Zonula adherens
• Adhesive strips or Fascia adherens
• Adhesive spot (Desmosomes, Maculae
adherens)
A. Communicating jns or gap jns

32. INTERCELLULAR JUNCTIONS
(JUNCTIONAL COMPLEXES)
ZONULA
OCCLUDENS
ZONULA
ADHERENS
DESMOSOME
HEMIDESMOSOME
GAP
JUNCTION

33. UNSPECIALISED CONTACT
• Cell adhesion molecules
• In intercellular gap
• Glycoprotein & proteoglycan

34. ZONULA OCCLUDENS
•Apical part of cell
•Band or belt
•Sealing effect
•Eg. Intestine, urinary bladder

35. DESMOSOME ZONULA ADHERENS
ANCHORING JUNCTIONS

36. GAP JUNCTION
•Lateral surface of epithelial cells
•Numerous transmembrane protein channels
•Permit inorganic ions, small molecules, nutrients,
chem messengers

37. TEST