SPECIALIZATIONS OF

EPITHELIAL CELLS

• BASAL

• APICAL

• LATERAL

APICAL DOMAIN

• STRUCTURAL MODIFICATION– CILIA – MICROVILLI– STEROCILIA

• SPECIFIC ENZYMES (HYDROLASES)

• ION CHANNELS

• CARRIER PROTEINS

BASAL DOMAIN

• BASEMENT MEMBRANE

• JUNCTIONS b/w cells & extra cellular structures

• INFOLDINGS OF PLASMA MEMBRANE

BASEMENT MEMBRANE

• SHEET LIKE EXTRACELLULAR MATERIAL

• PAS +ve

• BASAL LAMINA & RETICULAR LAMINA

• TWO BASAL LAMINA

BASAL LAMINA

• E/M 20-30nm• BASAL LAMINA A LAMINA DENSA B/W

2 LAMINA LUCIDA/ RARA• COMPONENTS SECRETED BY

EPITHELIAL CELLS – TYPE IV COLLAGEN, – GLYCOPROTEINS– PROTEOGLYCAN– ANCHORING FIBRILS (VII) BL & RL

RETICULAR LAMINA

• RETICULAR FIBERS TYPE III

• UNDER LYING CONNECTIVE TISSUE

• COARSE ALL DIRECTIONS

FUNCTIONS

• STRUCTURAL – attachment to underlying structures

• BARRIER & FILTRATION– Regulating movements

• REGENERATION

• Information for cell to cell interaction

• CELL POLIFERATION & DIFF. – Binding & concentrating growth factor

JUNCTIONS B/W CELLS & EXTRACELLULAR

STRUCTURES FOCAL ADHESION

HEMIDESMOSOMES

FOCAL ADHESION

• ACTIN OF CYTOSKELETON into BASEMENT MEMBRANE

• THRU TRANSMEMBRANE PROTEIN INTEGRIN

HEMIDESMOSOMES

• EPITHLIA subject to ABRASION SHEARING• CORNEA , SKIN, MUCOSA• HALF DESMOSOMES• ATTACHMENT PLAQUE • INTERMEDIATE FILAMENT INTO BASEMENT

MEMBRANE • PROTEIN INTEGRIN ( CADHERIN)• EXTRACELLUALR COMPONENT OF

INTEGRIN INTERACTS WITH LAMININ & TYPE IV COLLAGEN OF BASAL LAMINA

HEMIDESMOSOMES

•

INFOLDINGS OF BASAL PLASMA MEMBRANE

• FLUID TRANSPORTING CELLS

• PCT , DCT, STRIATED DUCTS

• MITOCHONDRIA

LATERAL DOMAINS

• APPOSED LATERAL DOMAINS

• UNIQUE PROTEINS & LIPIDS

• JUNCTIONAL COMPLEX

OCCLUDING JUNCTIONS

ANCHORING JUNCTIONS

COMMUNICATING JUNCTIONS

• FOLDS / PROCESSES

JUNCTIONAL COMPLEX

• OCCLUDING JUNCTIONSZONULA OCLUDENS

• ANCHORING JUNCTIONS ZONULA ADHERENS MACULA ADHERENCE

BASAL focal adhesion, hemidesmosome

TIGHT JUNCTIONSZONULA OCCLUDENS

• APICAL BAND• SERIES OF FOCAL ADHESION• OCClUDENS--- ZO---- ACTIN• BARRIER luminal &intercellular space• INTEGRITY OF DOMAINS• IMPERMEABILITY number of fusions• LIMITED RESISTANCE TO MECHANICAL

STRESS

ANCHORING JUNCTIONSZONULA ADHERENCE

• BELOW OCCLUDENS

• BAND reinforcing ZONULA OCCLUDENS

• 20-30nm space • TRANSMEMBRANE PROTEIN

CADHERIN- CATENIN-ACTIN (actinin,vinculin)

• MECHANICAL STABILITY

• FACIA ADHERENCE SHEET LIKE, CELLS OTHER THAN EPITHELIA

DESMOSOMES

• MACULA ADHERENCE• STRONG ATTACHMENT• SPOT JUNCTIONS• INTERCELLULAR SPACE 30nm• TRANS MEMBRANE PROTEIN

CADHERIN FAMILY (desmoglein & collin)

• ATTACHMENT PLAQUE (desmoplakin)

• INTERMEDIATE FILAMENT

GAP JUNCTIONNEXUS

• COMMUNICATING JUNCTIONS

• VARIOUS TISSUES (coordinated)– EPITHELIUM, SMOOTH & CARDIAC

MUSCLE, NERVOUS

• EXCHANGE(ions,regulatory mol.& small metabolite)

• TWO CONNEXONS

• Connexins 6 (dumbell)

• HYDROPHILIC PORE 2nm