LEcture 3 notes
Characteristics of all Epithelial Tissues 1. Cells are closely associated with little extracellular space 2. Cells are strongly attached via intracellular junctions 3. Line body surfaces and body cavities 4. Specialization - absorption, secretion,sensation, contractility 5. Cells are polarized 6. Epithelial tissues rest on a basement membrane
Basement Membrane = Basal Lamina Functions: 1) Structural attachment of epithelial cells to the CT 2) Compartmentalization. Isolate epithelial cells and muscle cells 3) Filtration. Movement of molecules is in part regulated by ionic charges (particularly important in the kidney) 4) Help to maintain the polarity of the epithelial tissues 5) Tissue scaffolding. Helps to scaffold regeneration (example: during nerve regeneration) Composition Proteoglycans, glycoproteins, collagen. A layer of reticular fibers underlies basement membranes
Hemidesmosome
Zonula Occludens
Zonula Adherens
Gap Junction
Desmosome Hemidesmosome
Hemidesmosome
Basement Membranes
Zonula Occludens
Membrane Proteins: Occludin, Claudin Cytoplasmic Proteins: ZO-1, actin, etc.
Zonula Adherens
α - actinin, vinculin Actin
Intercellular Space (15 nm) Cadherins
DESMOSOME (MACULA ADHERENS) Desmoplakins I and II, Plakoglobin, Desmocalmin
Intercellular Space (25 nm) Contains the Transmembrane Proteins Desmocollin and Desmoglein
Intermediate Filaments
HEMIDESMOSOME
Plaque Contains BP 200
Tonofilaments Plaque
TM Contains Transmembrane Proteins α6 Integrin, β4 Integrin and BP 180
PM TM
BM
Type VII Collagen The Term BP is related to Bullous Phemphigoid
GAP JUNCTION 2 nm
Coupled Connexons Channel (1.5 nm in Diameter)
Connexon (Composed of 6 connexins)
PM
Review of Epithelial Tissues Highly polarize – structure, migration, secretion, starting with BM Rest on Basement Membrane Some epithelial are stratified or simple of a variety of psudo-stratified Very little intracellular space Lots of junctional complexes : ZO, ZA, Desomsome, HemiDesomsomes, and Gap junctions .
Stem Cells
Nature Cell Biology 9:723
STEM CELL A
B Steady State: n(#) of newly originated cells by the stem cells are equal to the n (#) of dead cells on the surface of the epithelium. Turnover Time: is the time required to change the whole population of epithelial cells (30 days). Radiautography: provides a means to study the turnover of epithelial cells and of other cell types. Emulsion=Ag Br (silver bromide) 3H Thymidine (β-) + photographic development β-
Preprophase
Prophase
Metaphase
Intranuclear condensation of chromosomes
Visualization of chromosomes and mitotic spindle
Chromosomes in equatorial plane. Lost of nuclear envelope and nucleolus
Telophase
Nuclear restitution, nuclear envelope and nucleolar formation, end of cell division
Late Anaphase
Early Anaphase
Migration of chromosomes to the poles
Longitudinal splitting of chromosomes
Basement Membrane = Basal Lamina Functions: 1) Structural attachment of epithelial cells to the CT 2) Compartmentalization. Isolate epithelial cells and muscle cells 3) Filtration. Movement of molecules is in part regulated by ionic charges (particularly important in the kidney) 4) Help to maintain the polarity of the epithelial tissues 5) Tissue scaffolding. Helps to scaffold regeneration (example: during nerve regeneration) Composition Proteoglycans, glycoproteins, collagen. A layer of reticular fibers underlies basement membranes
Hemidesmosome
Zonula Occludens
Zonula Adherens
Gap Junction
Desmosome Hemidesmosome
Hemidesmosome
Basement Membranes
Zonula Occludens
Membrane Proteins: Occludin, Claudin Cytoplasmic Proteins: ZO-1, actin, etc.
Zonula Adherens
α - actinin, vinculin Actin
Intercellular Space (15 nm) Cadherins
DESMOSOME (MACULA ADHERENS) Desmoplakins I and II, Plakoglobin, Desmocalmin
Intercellular Space (25 nm) Contains the Transmembrane Proteins Desmocollin and Desmoglein
Intermediate Filaments
HEMIDESMOSOME
Plaque Contains BP 200
Tonofilaments Plaque
TM Contains Transmembrane Proteins α6 Integrin, β4 Integrin and BP 180
PM TM
BM
Type VII Collagen The Term BP is related to Bullous Phemphigoid
GAP JUNCTION 2 nm
Coupled Connexons Channel (1.5 nm in Diameter)
Connexon (Composed of 6 connexins)
PM
Review of Epithelial Tissues Highly polarize – structure, migration, secretion, starting with BM Rest on Basement Membrane Some epithelial are stratified or simple of a variety of psudo-stratified Very little intracellular space Lots of junctional complexes : ZO, ZA, Desomsome, HemiDesomsomes, and Gap junctions .
Stem Cells
Nature Cell Biology 9:723
STEM CELL A
B Steady State: n(#) of newly originated cells by the stem cells are equal to the n (#) of dead cells on the surface of the epithelium. Turnover Time: is the time required to change the whole population of epithelial cells (30 days). Radiautography: provides a means to study the turnover of epithelial cells and of other cell types. Emulsion=Ag Br (silver bromide) 3H Thymidine (β-) + photographic development β-
Preprophase
Prophase
Metaphase
Intranuclear condensation of chromosomes
Visualization of chromosomes and mitotic spindle
Chromosomes in equatorial plane. Lost of nuclear envelope and nucleolus
Telophase
Nuclear restitution, nuclear envelope and nucleolar formation, end of cell division
Late Anaphase
Early Anaphase
Migration of chromosomes to the poles
Longitudinal splitting of chromosomes
