[sometimes called vitelline sac; do not confuse with vitelline membrane of the egg; an embryonic membrane formed from endoderm and mesoderm; in reptiles and birds it incorporates the yolk into the digestive tract for nourishing the embryo; in placental mammals it is the source of most of the intestinal mucosa and the site of formation of the germ cells. ( CSP )]
UMLS (CSP) C0043425 Relation/PAR: embryo/fetus membrane