View source for Biology:Archenteron

{{Short description|Anatomical structure in a developing embryo}}
The '''archenteron''', also called the '''gastrocoel''' or the '''primitive digestive tube''', is the internal cavity of the primitive [[Biology:Gastrointestinal tract|gastrointestinal tract]] that forms during [[Biology:Gastrulation|gastrulation]] in a developing animal [[Biology:Embryo|embryo]]. It develops into the [[Biology:Endoderm|endoderm]] and [[Biology:Mesoderm|mesoderm]] of the animal.

==Formation in sea urchins==
{{further information|Biology:Gastrulation}}
As primary mesenchyme cells detach from the vegetal pole in the gastrula and enter the fluid-filled cavity in the center (the [[Biology:Blastocoel|blastocoel]]), the remaining cells at the vegetal pole flatten to form a vegetal plate. This buckles inwards towards the blastocoel in a process called [[Philosophy:Invagination|invagination]]. The cells continue to be rearranged until the shallow dip formed by invagination transforms into a deeper, narrower pouch formed by the gastrula's [[Biology:Endoderm|endoderm]]. This pouch narrows and lengthens to become the archenteron, a process driven by [[Biology:Convergent extension|convergent extension]]. The open end of the archenteron is called the blastopore.

[[File:Protovsdeuterostomes.svg|right|thumb|The archenteron is labeled as the digestive tube]]
The [[Biology:Filopodia|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 [[Biology:Ectoderm|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 [[Biology:Dorsal lip|dorsal lip]] in [[Biology:Amphibian|amphibian]]s and [[Biology:Fish|fish]], and the [[Biology:Primitive streak|primitive streak]] in [[Biology:Bird|bird]]s and [[Biology:Mammal|mammal]]s. Each is controlled by the dorsal lip and [[Biology:Primitive node|primitive node]] (also known as Hensen's node), respectively.

During [[Biology:Gastrulation|gastrulation]], the archenteron develops into the digestive tube, with the blastopore developing into either the mouth (in [[Biology:Protostome|protostome]]s) or the anus (in [[Biology:Deuterostome|deuterostome]]s).

==External links==
* [https://web.archive.org/web/20110709192109/http://chsweb.lr.k12.nj.us/mstanley/outlines/animals/antax/image51.gif Diagram]

{{Embryology}}
[[Category:Animal developmental biology]]


{{Sourceattribution|Archenteron}}