Meaning of YOLK SAC

WordNet Dictionary
	Definition:		[n]  membranous structure enclosing the yolk of eggs in birds reptiles marsupials and some fishes; circulates nutrients to the developing embryo [n]  membranous structure that functions as the circulatory system in mammal embryos until the heart becomes functional
	Websites:
	Synonyms:		umbilical vesicle, vesicula umbilicus, vitelline sac
	See Also:		sac
Glossary
	Definition:		a sack formed from embryonic tissue in the amniote egg that contains yolk.