Allantois

[ә'læntәuis]

Definition

(noun.) the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals).

Checked by Ives--From WordNet

Definition

(n.) Alt. of Allantoid

Checked by Hillel

Definition

n. a membranous sac-like appendage for effecting oxygenation in the embryos of mammals birds and reptiles.—adjs. Allantō′ic Allan′toid.

Inputed by Carlo