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

Recent Examples of yolk sac from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'yolk sac.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of yolk sac

1831


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

Learn More about yolk sac


Seen and Heard

What made you want to look up yolk sac? Please tell us where you read or heard it (including the quote, if possible).

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

marked by intense feeling

Get Word of the Day daily email!

Test Your Vocabulary

Find the Cousins

  • a-large-tree-with-many-branches
  • Which pair shares a common word ancestor?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!