allantois Meaning, Definition & Usage

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

WordNet

Al*lan"to*is, Al*lan"toid noun (Also<
  • Allantois
  • Allantoid
)
Definitions
  1. (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.

Webster 1913