Any of the membranes forming the investing envelope of the ovum.
These Food Names Aren’t What You Think They AreWhen you see mountain oysters on the menu, don’t expect a lovely plate of mollusks caught at the base of Black Mountain in San Francisco Bay.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Examples from the Web for egg membrane
When the tail of the larva has reached a very considerable length the egg-membrane bursts, and the larva becomes free.The Works of Francis Maitland Balfour, Volume III (of 4)|Francis Maitland Balfour