Convergent Extension

Intro

Convergent extension occurs when tissue needs to extend in one direction and shrink in another.

#1

The first step is to get rid of a junction between two cells in order to make room for new junctions to form.

• To get rid of a junction, there needs to be increased actomyosin contractility to pull the cells together, shrinking the contact between the cells that need to come apart.

Intro

Convergent extension occurs when tissue needs to extend in one direction and shrink in another.

#1

The first step is to get rid of a junction between two cells in order to make room for new junctions to form.

• To get rid of a junction, there needs to be increased actomyosin contractility to pull the cells together, shrinking the contact between the cells that need to come apart.

#2

As the zone of contact shrinks, clathrin is responsible for getting cadherin out of the cell so it can be recycled.

• The vesicle containing recycled cadherin fuses with an early endosome which is responsible for taking the cargo to the plasma membrane to be exocytosed out of the cell, so it can later be endocytosed(regulatory secretion) by another cell.

• When clathrin is inside the cell, the junction between cells is getting smaller. This means the cells we want to form junctions have been pulled together, creating an initial site of contact.

#3

Once the cells are in contact, Rac is activated which activates Arp2/3 to enlarge the zone of contact. This then activates RhoA whose purpose is to strengthen the new adhesions.

Conclusion

This process occurs with the purpose of dissolving the junctions between cells in one direction, so that new cell-cell junctions can form and the cell can extend in another direction.