Dictionary

yolk sac

noun

Definition of YOLK SAC

:  a membranous sac of most vertebrates that encloses the yolk, is attached in most forms (as in humans) through the yolk stalk with the intestinal cavity of the embryo, and is supplied with blood vessels that transport nutritive yolk products to the developing embryo

First Known Use of YOLK SAC

1861
Medical Dictionary

yolk sac

noun

Medical Definition of YOLK SAC

:  a membranous sac of most vertebrates that is attached to an embryo and encloses the yolk, that is continuous in most forms including humans through the omphalomesenteric duct with the intestinal cavity of the embryo, that is abundantly supplied with blood vessels which transport nutritive yolk products to the developing embryo, and that in placental mammals is nearly vestigial and functions chiefly prior to the formation of the placenta

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June 30, 2015
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