Transcript Cell Junction

Chapter 5
Cell Junction
Cell junction: specialized region of
connection between two cells or
between a cell and the extracelluar
matrix.
1. Tight junction
– zonula occludens
• Tight junction: Cell-cell
Tight
junction that seals adjacent
junction
epithelial cells together,
preventing the passage of
most dissolved molecules
from one side of the
epithelial sheet to the other.
Microvillus Tight junction
Adherens junction
Microvilli
Tight
junction
2. Desmosome
• Belt desmosome
(zonula adherens, adhesion belt,
adherens junction)
• Spot desmosome
(macula adherens)
• Hemidesmosome
2.1 Adhesion belt
(zonula adherens):
Beltlike adherens
junction that encircles
the apical end of an
epithelial cell and
attaches it to the
adjoining cell. A
contractile bundle of
actin filaments runs
along the cytoplasmic
surface of the adhesion
belt.
2.2 Spot desmosome: characterized by dense
plaques of protein into which intermediate
filaments in the two adjoining cells insert.
2.3 Hemidesmosome
3. Gap Junction
• Gap junction (nexus): Communicating cellcell junction that allows ions and small
molecules to pass from the cytoplasm of
one cell to the cytoplasm of the next.
large
gap
junction
membranes
small
gap
junction