Cell Junctions

Junctional complex (JC)

The point at which epithelial cells join to one another in very close proximity

Parts of JC

Zonula occludens (ZO)

Zonula adherens (ZA)

Macula adheres (MA) - aka desmosomes

Where are ZA and ZO found?

Forming a belt around the apex

Where is MA found?

Forming spot-like plaques on the cell

ZO

No intracellular space; outer laminae of adjacent membranes are fused

Not a stable connection

ZA

Binds to Actin to provide support' 10-20nm intercellular spaces

Gap (Connexon) junction

Form 1-1.5nm wide channel; site of low electrical resistance; point of cellular communication.

Strip like structure

Where are Connexon junctions found?

Along with the JC or alone - in smooth & cardiac muscle

Macula adheres characteristics

Increased densities resulting from attachment of intermediate micro filaments on the cytoplasmic side