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egg mem·brane, secondary egg membranetertiary egg membrane
the investing envelope of the oocyte; a primary egg membrane is produced from ovarian cytoplasm (for example, a vitelline membrane); a secondary egg membrane is the product of the ovarian follicle (for example, the zona pellucida); a tertiary egg membrane is secreted by the lining of the uterine tube (for example, a shell).
Farlex Partner Medical Dictionary © Farlex 2012
egg mem·brane, secondary egg membrane , tertiary egg membrane (eg mem'brān, sekŏn-dar-ē, tĕrshē-ăr-ē)
A primary egg membrane is produced from ovarian cytoplasm (e.g., a vitelline membrane); a secondary egg membrane is the product of the ovarian follicle (e.g., the zona pellucida); a tertiary egg membrane is secreted by the lining of the oviduct (e.g., a shell).
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
Any of the protective membranes or envelopes enclosing an ovum. It may be primary (formed by egg itself, as in vitelline membrane), secondary (formed by follicle cells, as in zona pellucida), or tertiary (formed by oviduct or uterus, as in albumin and shell of hen's egg).
See also: membrane
Medical Dictionary, © 2009 Farlex and Partners
egg membraneany membrane, shell or jelly-like layer surrounding and protecting the EGG, including primary membranes secreted by the OVUM or OOCYTE, secondary membranes secreted by cells of the ovary and tertiary membranes, for example albumen and egg shell, secreted by glands of the oviduct.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005