原腸
Archenteron \Arch`en"ter*on\, n. [Pref. arch- + Gr. ? intestine.] (Biol.) The primitive enteron or undifferentiated digestive sac of a gastrula or other embryo. See Illust. under {Invagination}.
archenteron n : central cavity of the gastrula; becomes the intestinal or digestive cavity