Archenteron
The archenteron, also called the gastrocoel, the primitive digestive tube or the primitive gut, is the internal cavity of the primitive gastrointestinal tract that forms during gastrulation in a developing animal embryo. It develops into the endoderm and mesoderm of the animal.
Formation in sea urchins
As
blastopore
.
The filopodia—thin fibers formed by the mesenchyme cells, found in late gastrulation—contract to drag the tip of the archenteron across the blastocoel. The endoderm of the archenteron will fuse with the ectoderm of the blastocoel wall. At this point gastrulation is complete, and the embryo has a functional digestive tube.
Similar formation process in other animals
The indentation that is actually formed is called the lip of the
blastopore or the dorsal lip in amphibians and fish, and the primitive streak in birds and mammals. Each is controlled by the dorsal lip and primitive node
(also known as Hensen's node), respectively.
During
blastopore developing into either the mouth (in protostomes) or the anus (in deuterostomes
).