[kawr-ee-oh-uh-lan-toh-is, ‐tois, kohr‐]
noun Embryology, Zoology.
a vascular, extraembryonic membrane of birds, reptiles, and certain mammals, formed by the fusion of the wall of the chorion with the wall of the allantois.
Origin of chorioallantois
First recorded in 1930–35
Also called chorioallantoic membrane.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
The highly vascular extraembryonic membrane formed by the fusion of the allantois with the chorion that constitutes the placenta in most mammals.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.