There are five types of cellular junctions present between epithelial cells: tight junctions, adhering junctions, desmosomes, gap junctions, and hemidesmosomes. Tight junctions prevent molecules from passing between cells and control fluid movement. Adhering junctions tightly adhere adjacent cells together using proteins like E-cadherins. Desmosomes also adhere cells using proteins like desmocollins and desmogleins, though they are not as strong as adhering junctions. Gap junctions allow communication between cells using connexon protein channels. Hemidesmosomes attach the basal surface of epithelial cells to the extracellular matrix using integrin proteins and intermediate filaments.

1. INTERCELLUAR
CONNECTIONS BETWEEN
EPITHELIAL CELLS
Ladi Anudeep
ISM-IUK

3. • Five types of cellular junctions are present in between
the epithelial cells
• 1) Tight junctions or Zona occludens
• 2) Adhering junctions or Zona adherens
• 3) Desmosomes or Macula adherens
• 4) Gap junctions or Connexons
• 5) Hemidesmosomes

4. ZONA OCCLUDENS
>This is the example of tight junction
>It is present in the lateral surfaces of epithelial cells
>They help in stiching the cells together
>These are the special structures around the cell as to
attatch with surrounding cells
>Zona occludens prevents floating of protein channels from
apical surface to basal surface
>It controls fluid movement through paracellular route

5. • Zona occludens is a membrane protein complex that
made up of special type proteins called occludens and
claudins
• Occludens and claudins come out of cell membrane and
interact with each other and seal the surface of two
adjacent cells
• These two proteins are attatched to three proteins called
ZO1, ZO2, ZO3.
• These three proteins helps in holding occludens and
claudins properly in their positions.
• This type of junction is present at apical region.

6. ZONA ADHERENS
• This is the example for adhering junctions present just
below to tight junctions.
• They help in tightly adhering the adjacent cells together.
• This is like a sticky belt present around the cell.
• E.cadherins are the proteins helping in sticking the cells
together in the presence of calcium.
• Vinculin is the protein present in the inner side of cell
which is further attatched to the alpha actinin and
catenin.
• the cytoskeleton filaments which are attatched to alpha
actinin are actin filaments.

7. MACULA ADHERENS
• This is an example for desmosomes.
• Macula means a spot like.
• This is also helpful for sticking the cells together but in
only some places.
• These are not as strong as zona adherens.
• The proteins which are helpful for adhering here are
Desmocollins and Desmogleins.
• This is also calcium based attatchment.
• Inside the cell, there is a special disc present which is
made up of desmoplachins and plakoglobins.
• The cytoskeletal filaments attatched to this disc are
intermediate fillaments and tonofillaments( keratin)

8. GAP JUNCTIONS
• These are the window like structures present on the
lateral surface of each epithelial cells for the sake of
communication between the cells.
• It is made up of 6 types of proteins made up of
connexins, so these 6 connexins combine to form a
protein channel called connexon.
• These can be opened or closed when neccesary.

9. HEMIDESMOSOMES
• These are the only celluar junctions present on the basal
surface of the epithelium.
• Integrins are the proteins which are present on basal cell
membrane.
• Hemidesmosomes through integrin attacthes to extra
cellular material.
• Inside hemidesmosomes have special type of fillaments
of cytoskeleton called as intermediate fillaments .

10. HEMIDESMOSOMES
• These are the only celluar junctions present on the basal
surface of the epithelium.
• Integrins are the proteins which are present on basal cell
membrane.
• Hemidesmosomes through integrin attacthes to extra
cellular material.
• Inside hemidesmosomes have special type of fillaments
of cytoskeleton called as intermediate fillaments .