This document discusses epithelial tissue and its functions. It describes the different types of epithelial cells including covering, glandular, neuroepithelial and myoepithelial cells. It outlines the components and functions of the basal lamina. It details the polarity, layers, shapes and types of epithelia including simple, stratified, pseudostratified, squamous, cuboidal and columnar. It examines the intercellular junctions that provide cohesion and communication between epithelial cells. It describes microvilli, cilia and glandular epithelia. It discusses the nutrition and renewal of epithelial tissues.

1. EPITHELIAL TISSUE
CONNECTIVE TISSUE
MUSCULAR TISSUE
NERVOUS TISSUE

2. Oral cavity
Skin
Digestive
Tract
Peritoneum
Respiratory
Passages
Pleural
cavities
Hart and
Blood vessels
Pericardium
Urinary tracts
Glands
Limph vessels

3. FUNCTIONS OF EPITHELIA
COVERING EPITHELIA
covering of surfaces and lining of cavities
protection of covered tissue
absorption - intestines, proximal tubules of kidney
GLANDULAR EPITHELIA
secretion - exocrine glands
NEUROEPITHELIAL CELLS
sensation - olfactory epithelium , taste buds
MYOEPITHELIAL CELLS
contractility - salivary glands, sweat glands

5. COMPONENTS OF BASAL
LAMINA
COLLAGEN TYPE IV
LAMININ, FIBRONECTIN
(glycoproteins)
PROTEOGLYCANS (HEPARAN SULFATE)
ANCHORING FIBRILS COLLAGEN TYPE VII

6. FUNCTIONS OF BASAL
LAMINA
Selective barrier between connective tissue
and epithelium
Adhesion of the connective tissue and
the epithelium

7. POLARITY OF EPITHELIA
APICAL SURFACE
BASAL SURFACE - rests on basal lamina

8. TYPES OF EPITHELIA
ACCORDING TO NUMBER OF LAYERS
simple
stratified
pseudostratified
ACCORDING TO SHAPE OF CELLS
squamous
cuboidal
columnar

9. SIMPLE SQUAMOUS EPITHELIUM
endothelium, mesothelium

10. SIMPLE SQUAMOUS EPITHELIUM

11. SIMPLE CUBOIDAL EPITHELIUM
proximal and distal renal tubules

12. SIMPLE CUBOIDAL EPITHELIUM

13. SIMPLE COLUMNAR EPITHELIUM
stomach, small and large intestine,
oviduct

14. SIMPLE COLUMNAR EPITHELIUM

15. PSEUDOSTRATIFIED EPITHELIUM
respiratory passages, epididymis

16. STRATIFIED SQUAMOUS EPITHELIUM
keratinised - skin
nonkeratinised - oral cavity, vagina

17. STRATIFIED SQUAMOUS EPITHELIUM
keratinised
Skin
nonkeratinised
Cornea
Esophagus

18. STRATIFIED COLUMNAR EPITHELIUM
ocular conjunctiva

19. TRANSITIONAL EPITHELIUM
urinary bladder, ureter

20. INTERCELLULAR
JUNCTIONS
membrane associated structures responsible
for cohesion and communication between
cells
ADHERING JUNCTIONS
IMPERMEABLE JUNCTIONS
COMMUNICATING JUNCTIONS

21. TIGHT JUNCTION ZONULA OCCLUDENS
LOCATION - the most apical
SHAPE - band encircling the cell
MORPHOLOGY - network of linear fusion
sites between membrane associated proteins
FUNCTION - close off the intercellular space
(leakiness of the epithelium)

22. TIGHT JUNCTION ZONULA
OCCLUDENS

23. Prevent
the flow
between
the cells
Prevent the
movement
of membrane
proteins
TIGHT JUNCTION ZONULA
OCCLUDENS

24. DESMOSOME

25. DESMOSOME MACULA ADHERENS
LOCATION - along the lateral membranes
DISK-SHAPED
MORPHOLOGY attachment plaques - desmoplaquin
intercellular space - desmoglein
cytokeratin filaments
FUNCTION - very firm adhesion of
neighbor-cells

26. ZONULA ADHERENS

27. ZONULA ADHERENS
LOCATION - just below tight junction
SHAPE - band encircling the cell
MORPHOLOGY dense plagues - α -actinin, vinculin,
myosin, tropomyosin
intercellular space - E-kadherin and
calcium ions
actin-containing microfilaments
FUNCTION - adhesion of neighbor-cells

28. HEMIDESMOSOME
LOCATION - contact zone
between epithelium and basal
lamina
DISK-SHAPED
MORPHOLOGY - half a
desmosome
FUNCTION - binds the epithelial
cell to basal lamina

29. INTERCELLULAR
JUNCTIONS
Electron transmission
microscope

30. GAP JUNCTION NEXUS
LOCATION - anywhere along the lateral
membranes of epithelial cells
MORPHOLOGY - hexamers of proteins
with a hydrophilic pore in the center
(connexon)
FUNCTION - interchange of small
molecules between adjacent cells (cyclic
AMP, ions)

31. GAP JUNCTION NEXUS

32. GAP JUNCTION - NEXUS

33. MICROVILLI
Extension of cytoplasm 1µ m long
Actin-containing
microfilaments
FUNCTION - increase
the surface area
LIGHT MICROSCOPE
- BRUSH BORDER

34. MICROVILLI

35. MICROVILLI – brush border

36. CILIA
LONG PROJECTIONS - 10 µ m
MOTILE
STRUCTURE:
central pair of microtubuls
9 pairs at the periphery
INSERTED INTO BASAL BODIES
FUNCTION - permit a current of
material over epithelium

37. CILIA

38. STEREOCILIA long microvilli
FLAGELLA similar in structure to cilia

39. GLANDULAR
EPITHELIA - Glands
FUNCTION secretion of
products which are
used in other parts
of the organism

43. SEROUS GLANDS
ACINAR SECRETORY PORTIONS
SECRET CLEAR FLUID SECRETION
SEROUS CELLS:
ruonded nucleus at basal part of
cytoplasm
abundant RER –
basophilic cytoplasm
well visible secretory
granules at the apex

44. SEROUS CELLS

45. MUCOUS GLANDS
TUBULAR SECRETORY
PORTIONS
SECRET MUCUS
MUCOUS CELLS
flat nucleus at
the basis
large, translucent
secretory granules
well developed
Golgi complex

49. SUBLINGUAL GLANDS

50. TYPES OF EXOCRINE GLANDS
APOCRINE
HOLOCRINE
secretory product is
discharged with
apical part of
cytoplasm
secretory product is
shed with whole cell
MEROCRINE
secretory granules leave
the cell by exocytosis

52. NUTRITION OF EPITHELIA
NO BLOOD VESSELS IN EPITHELIA
NUTRIENTS AND PRECURSORS OF
PRODUCTS DIFFUSE FROM
CONNECTIVE TISSUE ACROSS THE
BASAL LAMINA TO EPITHELIAL CELLS

53. RENEWAL
REPLACEMENT OF OLD CELLS BY
NEW ONES
MITOTIC DIVISIONS
OCCUR IN ALL EPITHELIA