yolk sac

Definitions of yolk sac
1

n membranous structure enclosing the yolk of eggs in birds, reptiles, marsupials, and some fishes; circulates nutrients to the developing embryo

Type of:
sac
a structure resembling a bag in an animal

n membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional

Synonyms:
umbilical vesicle, vesicula umbilicus, vitelline sac
Type of:
sac
a structure resembling a bag in an animal

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