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yolk sac

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Egg sac
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yolk sac

 
Use yolk sac in a Sentence
–noun Embryology.
1. an extraembryonic membrane that encloses the yolk of eggs in birds, reptiles, and marsupials and that circulates nourishment from the yolk to the developing embryo.
2. a similar membrane in placental mammals that encloses a mostly hollow space and loses its nutritive function entirely as the placenta develops.
Origin:
1860–65
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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Egg sac
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www.RightHealth.com/Cysts
yolk sac  
n.  A membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals and functioning as the circulatory system of the human embryo before internal circulation begins.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Medical Dictionary

Main Entry: yolk sac
Function: noun
: a membranous sac that is attached to an embryo and encloses food yolk, that is continuous in most forms through theomphalomesenteric duct with the intestinal cavity of the embryo, that being abundantly supplied with blood vessels is throughout embryonic life and in some forms later the chief organ of nutrition, andthat in placental mammals is nearly vestigial and functions chiefly prior to the formation of the placenta
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Medical Dictionary

yolk sac n.
A membranous sac attached to an embryo, enclosing food yolk. Also called umbilical vesicle.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Science Dictionary
yolk sac  
A sac that is attached to the gut of an embryo and encloses the yolk in bony fish, sharks, reptiles, mammals, and birds. In most mammals, the yolk sac functions as part of the embryo's circulatory system before the placenta develops.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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