Hensen’s Node Retreats

• Hensen’s Node leaves behind the head process

• Differentiation begins in individual cells as soon as Hensen’s Node has retreated

• Anterior end more developed than the posterior end

Previous slide

Next slide

Back to first slide

View graphic version

Once Hensen’s Node reaches the most anterior end of the embryo, it begins to retreat again, leaving behind the head process, a group of cells that will eventually form the structures of the chick’s head. The last cells to pass through the streak as it recedes are destined to become the notochord

The recession of Hensen’s Node marks the beginning of a new phase of development, in which structures begin to differentiate. Since Hensen’s node recedes from the anterior end first, the development at the anterior end begins sooner than at the posterior end. Therefore, the anterior to posterior gradient of maturity is evident.