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1. An extracellular coat that surrounds the egg in invertebrates and most nonmammalian vertebrates. Also called vitelline envelope.
2. The zona pellucida.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
vitelline membrane(vɪˈtɛlɪn; -aɪn)
(Zoology) zoology a membrane that surrounds a fertilized ovum and prevents the entry of other spermatozoa
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
the membrane surrounding an egg yolk.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.