Histology Notes

3. SPECIALIZATIONS
OF
EPITHELIAL CELLS
• BASAL
• APICAL
• LATERAL

4. APICAL DOMAIN
• STRUCTURAL MODIFICATION
– CILIA
– MICROVILLI
– STEROCILIA
• SPECIFIC ENZYMES (HYDROLASES)
• ION CHANNELS
• CARRIER PROTEINS

5. BASAL DOMAIN
• BASEMENT MEMBRANE
• JUNCTIONS b/w cells & extra cellular
structures
• INFOLDINGS OF PLASMA MEMBRANE

6. BASEMENT MEMBRANE
• SHEET LIKE EXTRACELLULAR
MATERIAL
• PAS +ve
• BASAL LAMINA & RETICULAR LAMINA
• TWO BASAL LAMINA

8. 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

9. RETICULAR LAMINA
• RETICULAR FIBERS TYPE III
• UNDER LYING CONNECTIVE TISSUE
• COARSE ALL DIRECTIONS

10. FUNCTIONS
• STRUCTURAL
– attachment to underlying structures
• BARRIER & FILTRATION
– Regulating movements
• REGENERATION
• Information for cell to cell interaction
• CELL POLIFERATION & DIFF.
– Binding & concentrating growth factor

11. JUNCTIONS B/W CELLS &
EXTRACELLULAR
STRUCTURES
FOCAL ADHESION
HEMIDESMOSOMES

12. FOCAL ADHESION
• ACTIN OF
CYTOSKELETON
into BASEMENT
MEMBRANE
• THRU
TRANSMEMBRANE
PROTEIN INTEGRIN

13. 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

14. HEMIDESMOSOMES
•

15. INFOLDINGS OF BASAL PLASMA
MEMBRANE
• FLUID
TRANSPORTING
CELLS
• PCT , DCT,
STRIATED DUCTS
• MITOCHONDRIA

16. LATERAL DOMAINS
• APPOSED LATERAL DOMAINS
• UNIQUE PROTEINS & LIPIDS
• JUNCTIONAL COMPLEX
OCCLUDING JUNCTIONS
ANCHORING JUNCTIONS
COMMUNICATING JUNCTIONS
• FOLDS / PROCESSES

17. JUNCTIONAL COMPLEX
• OCCLUDING JUNCTIONS
ZONULA OCLUDENS
• ANCHORING JUNCTIONS
ZONULA ADHERENS
MACULA ADHERENCE
BASAL focal adhesion,
hemidesmosome

18. TIGHT JUNCTIONS
ZONULA 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

20. ANCHORING JUNCTIONS
ZONULA 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

22. DESMOSOMES
• MACULA ADHERENCE
• STRONG ATTACHMENT
• SPOT JUNCTIONS
• INTERCELLULAR SPACE 30nm
• TRANS MEMBRANE PROTEIN
CADHERIN FAMILY (desmoglein & collin)
• ATTACHMENT PLAQUE (desmoplakin)
• INTERMEDIATE FILAMENT

24. GAP JUNCTION
NEXUS
• COMMUNICATING JUNCTIONS
• VARIOUS TISSUES (coordinated)
– EPITHELIUM, SMOOTH & CARDIAC
MUSCLE, NERVOUS
• EXCHANGE(ions,regulatory mol.& small metabolite)
• TWO CONNEXONS
• Connexins 6 (dumbell)
• HYDROPHILIC PORE 2nm