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