EPITHELIAL TISSUES

CHARACTERISTICS : Derived from the three germ layers Covering and Lining Tissue Highly cellular tissue Diverse function Forms the parenchyma of organs Avascular tissue Exhibits polarity High rate of turnover of cells

COMPONENTS OF E.T.A. CELLS – flattened squamous,

cuboidal, columnar, intermediate / transitional forms

B. INTERCELLULAR SUBSTANCE

BASEMENT MEMBRANEFormed by the :

1) Basal Lamina a. Lamina densa b. Lamina lucida

2) Reticular Lamina

INTERCELLULAR JUNCTIONS

OCCLUDING JUNCTIONS

GAP JUNCTIONS

ADHESIVE /ANCHORING JUNCTIONS

ADHESIVE /ANCHORING JUNCTIONS

A.ZONULA ADHERENS B. FOCAL CONTACTS

ADHESIVE /ANCHORING JUNCTIONS

A. DESMOSOMES B. HEMIDESMOSOMES

SPECIALIZATION ON APICAL SURFACES OF EPITH. CELL

A. MICROVILLI B. STEREOCILIA

SPECIALIZATION SEEN ONEPITH. CELL

C. CILIA/FLAGELLUM D. BASAL INFOLDINGS

MAIN GROUPS OF EPITHELIUM

I. EPITHELIAL MEMBRANE – includes the covering and lining epithelia

II. EPITHELIAL GLANDS

BASIS OF NOMENCLATURE OFEPITHELIAL MEMBRANE

1. Number of Cell Layers –A. SimpleB. Stratified / Complex

2. Shape of the Component Cells / or the

Shape of Cells on the Outermost Layer 3. Presence of Surface Specialization

SIMPLEEPITHELIA

SIMPLE SQUAMOUS SQUAMOUS EPITH. A. ENDOTHELIUM

SIMPLE SQUAMOUSB. MESOTHELIUM

C. FLATTENED EPITHELIUM

SIMPLE SQUAMOUSC. FLATTENED EPITHELIUM

PAVEMENT EPITHELIUM

SIMPLE CUBOIDAL

SIMPLE COLUMNAR

STRATIFIED SQUAMOUSA. KERATINIZED B. NON KERATINIZED

STRATIFIED EPITHELIAA. STRAT. COLUMNAR B. STRAT. CUBOIDAL

TRANSITIONAL EPITHELIA

PSEUDOSTRATIFIED COLUMNAR EPITH.

EPITHELIAL GLANDS(CLASSIFICATION)