Definition of yolk sac in English:

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yolk sac


1A membranous sac containing yolk attached to the embryos of reptiles and birds and the larvae of some fishes.
Example sentences
  • The eggs take about 20 weeks to hatch and the now free-swimming ray is still reliant upon its yolk sac for a few more weeks before it begins to feed upon shrimps.
  • Likewise, the occasional yolk sac tumor arising in liver has been reported in childhood.
  • The neoplasm metastasized as the yolk sac component.
1.1A sac lacking yolk in the early embryo of a mammal.

For editors and proofreaders

Syllabification: yolk sac

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