Hypertext Webster Gateway: "allantois"
From Webster's Revised Unabridged Dictionary (1913) (web1913)
Allantois \Al*lan"to*is\, Allantoid \Al*lan"toid\, ] n.. (Anat.)
A membranous appendage of the embryos of mammals, birds, and
reptiles, -- in mammals serving to connect the fetus with the
parent; the urinary vesicle.
From WordNet (r) 1.7 (wn)
allantois
n : vascular fetal membrane that develops from the hindgut in
embryonic higher vertebrates (mammals; birds; reptiles)
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