primitive streak

primitive streak definition - medical

primitive streak

noun
An ectodermal ridge in the midline at the caudal end of the embryonic disk from which the intraembryonic mesoderm arises.

The American Heritage® Medical Dictionary Copyright © 2009 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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