EPITHELIAL TISSUEEPITHELIAL TISSUE

CONNECTIVE TISSUECONNECTIVE TISSUE

MUSCULAR TISSUEMUSCULAR TISSUE

NERVOUS TISSUENERVOUS TISSUE

Oral cavity

Skin

Digestive Tract

Peritoneum

Respiratory Passages

Pleural cavities

Hart andBlood vessels

Pericardium

Urinary tracts

Glands

Limph vessels

FUNCTIONS OF EPITHELIAFUNCTIONS OF EPITHELIA

COVERING EPITHELIACOVERING EPITHELIA

covering of surfaces and lining of cavitiescovering of surfaces and lining of cavities

protection protection of covered tissueof covered tissue

absorption absorption -- intestines, proximal tubules of kidneyintestines, proximal tubules of kidney

GLANDULAR EPITHELIAGLANDULAR EPITHELIA

secretionsecretion - exocrine glands - exocrine glands

NEUROEPITHELIAL CELLSNEUROEPITHELIAL CELLS

sensation sensation - olfactory epithelium , taste buds - olfactory epithelium , taste buds

MYOEPITHELIAL CELLSMYOEPITHELIAL CELLS

contractility contractility -- salivary glands, sweat glands salivary glands, sweat glands

COMPONENTS OF BASAL COMPONENTS OF BASAL LAMINALAMINA

� COLLAGEN TYPE IVCOLLAGEN TYPE IV

� LAMININ, FIBRONECTIN LAMININ, FIBRONECTIN

(glycoproteins)(glycoproteins)

� PROTEOGLYCANSPROTEOGLYCANS - -

(HEPARAN SULFATE)(HEPARAN SULFATE)

� ANCHORING FIBRILS ANCHORING FIBRILS --

COLLAGEN TYPE VIICOLLAGEN TYPE VII

FUNCTIONS OF BASAL FUNCTIONS OF BASAL LAMINALAMINA

Selective barrier between connective tissue Selective barrier between connective tissue

and epitheliumand epithelium

Adhesion of the connective tissue and Adhesion of the connective tissue and

the epitheliumthe epithelium

POLARITY OF EPITHELIAPOLARITY OF EPITHELIA

APICAL SURFACE APICAL SURFACE

BASAL SURFACE - rests on basal laminaBASAL SURFACE - rests on basal lamina

TYPES OF EPITHELIATYPES OF EPITHELIA

ACCORDING TO NUMBER OF LAYERSACCORDING TO NUMBER OF LAYERS

simplesimple

stratifiedstratified

pseudostratifiedpseudostratified

ACCORDING TO SHAPE OF CELLSACCORDING TO SHAPE OF CELLS

squamoussquamous

cuboidalcuboidal

columnarcolumnar

SIMPLE SQUAMOUS EPITHELIUM SIMPLE SQUAMOUS EPITHELIUM

endothelium, mesotheliumendothelium, mesothelium

SIMPLE SQUAMOUS EPITHELIUM SIMPLE SQUAMOUS EPITHELIUM

SIMPLE CUBOIDAL EPITHELIUM SIMPLE CUBOIDAL EPITHELIUM

proximal and distal renal tubulesproximal and distal renal tubules

SIMPLE CUBOIDAL EPITHELIUMSIMPLE CUBOIDAL EPITHELIUM

SIMPLE COLUMNAR EPITHELIUM SIMPLE COLUMNAR EPITHELIUM

stomach, small and large intestine, stomach, small and large intestine, oviductoviduct

SIMPLE COLUMNAR EPITHELIUM SIMPLE COLUMNAR EPITHELIUM

PSEUDOSTRATIFIED EPITHELIUM PSEUDOSTRATIFIED EPITHELIUM

respiratory passages, epididymisrespiratory passages, epididymis

STRATIFIED SQUAMOUS EPITHELIUM STRATIFIED SQUAMOUS EPITHELIUM

keratinised - skinkeratinised - skin

nonkeratinised - oral cavity, vaginanonkeratinised - oral cavity, vagina

STRATIFIED SQUAMOUS EPITHELIUMSTRATIFIED SQUAMOUS EPITHELIUM

keratinisedkeratinised nonkeratinisednonkeratinised

Skin Cornea Esophagus

STRATIFIED COLUMNAR EPITHELIUM STRATIFIED COLUMNAR EPITHELIUM

ocular conjunctivaocular conjunctiva

TRANSITIONAL EPITHELIUM TRANSITIONAL EPITHELIUM

urinary bladder, ureterurinary bladder, ureter

INTERCELLULAR INTERCELLULAR JUNCTIONSJUNCTIONS

membrane associated structures responsible membrane associated structures responsible for cohesion and communication between for cohesion and communication between cellscells

ADHERING JUNCTIONSADHERING JUNCTIONS

IMPERMEABLE JUNCTIONSIMPERMEABLE JUNCTIONS

COMMUNICATING JUNCTIONSCOMMUNICATING JUNCTIONS

TIGHT JUNCTION - TIGHT JUNCTION - ZONULA OCCLUDENSZONULA OCCLUDENS

LOCATION - the most apicalLOCATION - the most apical

SHAPE - band encircling the cellSHAPE - band encircling the cell

MORPHOLOGY - network of linear fusion MORPHOLOGY - network of linear fusion

sites between membrane associated proteinssites between membrane associated proteins

FUNCTION - close off the intercellular space FUNCTION - close off the intercellular space

(leakiness of the epithelium)(leakiness of the epithelium)

TIGHT JUNCTION - TIGHT JUNCTION - ZONULA ZONULA

OCCLUDENSOCCLUDENS

TIGHT JUNCTION - TIGHT JUNCTION - ZONULA ZONULA

OCCLUDENSOCCLUDENS

Preventthe flowbetween the cells

Prevent the movement of membrane proteins

DESMOSOMEDESMOSOME

DESMOSOME -DESMOSOME -MACULA ADHERENSMACULA ADHERENS

LOCATION - along the lateral membranesLOCATION - along the lateral membranes

DISK-SHAPED DISK-SHAPED

MORPHOLOGY -MORPHOLOGY -

attachment plaques - desmoplaquinattachment plaques - desmoplaquin

intercellular space - desmogleinintercellular space - desmoglein

cytokeratin filaments cytokeratin filaments

FUNCTION - very firm adhesion of FUNCTION - very firm adhesion of neighbor-cellsneighbor-cells

ZONULA ADHERENSZONULA ADHERENS

ZONULA ADHERENSZONULA ADHERENSLOCATION - just below tight junctionLOCATION - just below tight junction

SHAPE - band encircling the cellSHAPE - band encircling the cell

MORPHOLOGY -MORPHOLOGY -

dense plagues - dense plagues - αα -actinin, vinculin, -actinin, vinculin, myosin, tropomyosinmyosin, tropomyosin

intercellular space - E-kadherin and intercellular space - E-kadherin and calcium ionscalcium ions

actin-containing microfilamentsactin-containing microfilaments

FUNCTION - adhesion of neighbor-cellsFUNCTION - adhesion of neighbor-cells

HEMIDESMOSOMEHEMIDESMOSOME

LOCATION - contact zone LOCATION - contact zone

between epithelium and basal between epithelium and basal

laminalamina

DISK-SHAPEDDISK-SHAPED

MORPHOLOGY - half a MORPHOLOGY - half a

desmosomedesmosome

FUNCTION - binds the epithelial FUNCTION - binds the epithelial

cell to basal laminacell to basal lamina

INTERCELLULAR INTERCELLULAR JUNCTIONSJUNCTIONS

Electron transmission microscope

GAP JUNCTION -GAP JUNCTION -NEXUS NEXUS

LOCATION - anywhere along the lateral LOCATION - anywhere along the lateral membranes of epithelial cellsmembranes of epithelial cells

MORPHOLOGY - hexamers of proteins MORPHOLOGY - hexamers of proteins with a hydrophilic pore in the center with a hydrophilic pore in the center (connexon)(connexon)

FUNCTION - interchange of small FUNCTION - interchange of small molecules between adjacent cells (cyclic molecules between adjacent cells (cyclic AMP, ions) AMP, ions)

GAP JUNCTION -GAP JUNCTION -NEXUSNEXUS

GAP JUNCTION - NEXUSGAP JUNCTION - NEXUS

MICROVILLIMICROVILLI

Extension of cytoplasm - Extension of cytoplasm -

11µµ m longm long

Actin-containing Actin-containing

microfilamentsmicrofilaments

FUNCTION - increase FUNCTION - increase

the surface areathe surface area

LIGHT MICROSCOPE LIGHT MICROSCOPE

- BRUSH BORDER - BRUSH BORDER

MICROVILLIMICROVILLI

MICROVILLI – brush borderMICROVILLI – brush border

CILIACILIA

LONG PROJECTIONS - 10 LONG PROJECTIONS - 10 µµmm

MOTILEMOTILE

STRUCTURE:STRUCTURE:

central pair of microtubulscentral pair of microtubuls

9 pairs at the periphery9 pairs at the periphery

INSERTED INTO BASAL BODIESINSERTED INTO BASAL BODIES

FUNCTION - permit a current of FUNCTION - permit a current of material over epitheliummaterial over epithelium

CILIACILIA

STEREOCILIA - STEREOCILIA - long microvillilong microvilli

FLAGELLA - FLAGELLA - similar in structure to ciliasimilar in structure to cilia

GLANDULAR GLANDULAR EPITHELIA - GlandsEPITHELIA - Glands FUNCTION - FUNCTION -

secretion of secretion of

products which are products which are

used in other parts used in other parts

of the organismof the organism

SEROUS GLANDSSEROUS GLANDSACINAR SECRETORY PORTIONSACINAR SECRETORY PORTIONS

SECRET CLEAR FLUID SECRETIONSECRET CLEAR FLUID SECRETION

SEROUS CELLS:SEROUS CELLS:

ruonded nucleus at basal part of ruonded nucleus at basal part of

cytoplasm cytoplasm

abundant RER – abundant RER –

basophilic cytoplasmbasophilic cytoplasm

well visible secretory well visible secretory

granules at the apexgranules at the apex

SEROUS CELLSSEROUS CELLS

MUCOUS GLANDSMUCOUS GLANDSTUBULAR SECRETORY TUBULAR SECRETORY

PORTIONSPORTIONS

SECRET MUCUSSECRET MUCUS

MUCOUS CELLSMUCOUS CELLS

� flat nucleus at flat nucleus at

the basisthe basis

� large, translucent large, translucent

secretory granulessecretory granules

� well developed well developed

Golgi complexGolgi complex

SUBLINGUAL GLANDSSUBLINGUAL GLANDS

TYPES OF EXOCRINE GLANDSTYPES OF EXOCRINE GLANDS

APOCRINEsecretory product is discharged with apical part of cytoplasm

MEROCRINEsecretory granules leave the cell by exocytosis

HOLOCRINEsecretory product is shed with whole cell

NUTRITION OF EPITHELIANUTRITION OF EPITHELIA

NO BLOOD VESSELS IN EPITHELIANO BLOOD VESSELS IN EPITHELIA

NUTRIENTS AND PRECURSORS OF NUTRIENTS AND PRECURSORS OF PRODUCTS DIFFUSE FROM PRODUCTS DIFFUSE FROM CONNECTIVE TISSUE ACROSS THE CONNECTIVE TISSUE ACROSS THE BASAL LAMINA TO EPITHELIAL CELLSBASAL LAMINA TO EPITHELIAL CELLS

RENEWALRENEWAL

REPLACEMENT OF OLD CELLS BY REPLACEMENT OF OLD CELLS BY NEW ONESNEW ONES

MITOTIC DIVISIONSMITOTIC DIVISIONS

OCCUR IN ALL EPITHELIAOCCUR IN ALL EPITHELIA