ALL meanings of allantois
al·lan·to·is
A a - noun allantois a membranous sac growing out of the ventral surface of the hind gut of embryonic reptiles, birds, and mammals. It combines with the chorion to form the mammalian placenta 3
- noun allantois a membranous pouch with a rich blood supply in the embryos of birds, reptiles, and mammals: it is an organ of respiration and excretion for embryonic birds and reptiles: in mammals it helps form the placenta 3
- noun allantois The fetal membrane lying below the chorion in many vertebrates, formed as an outgrowth of the embryo’s gut. In birds and reptiles it grows to surround the embryo; in eutherian mammals it forms part of the placenta. 1
- noun allantois a vascular, extraembryonic membrane of birds, reptiles, and certain mammals that develops as a sac or diverticulum from the ventral wall of the hindgut. 1
- noun allantois (anatomy) A sac, having a number of functions, that develops in the alimentary canal of the embryos of mammals, birds and reptiles. 0