| umls-concept:C0002084 | skos:definition | MSH: An extra-embryonic membranous sac derived from the YOLK SAC of REPTILES; BIRDS; and MAMMALS. It lies between two other extra-embryonic membranes, the AMNION and the CHORION. The allantois serves to store urinary wastes and mediate exchange of gas and nutrients for the developing embryo.,NCI: An extraembryonic membrane in the form of a sac. It collects waste from the embryo. | lld:umls |
