allantois
a vascular, extraembryonic membrane of birds, reptiles, and certain mammals that develops as a sac or diverticulum from the ventral wall of the hindgut.
Origin of allantois
1Words Nearby allantois
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024
How to use allantois in a sentence
The cavity of the allantois, if developed, vanishes completely.
The Works of Francis Maitland Balfour, Volume III (of 4) | Francis Maitland BalfourThis bag is called the allantois, and serves as a sort of lung for the developing chick.
The Meaning of Evolution | Samuel Christian SchmuckerIt draws its oxygen and throws off its wastes through the instrumentality of the allantois, which covers it over.
The Meaning of Evolution | Samuel Christian SchmuckerThe blood vessels of the allantois take in oxygen and give out carbon dioxide through the porous shell.
The Meaning of Evolution | Samuel Christian SchmuckerThe allantois of the chick now gains a new development and an altered function.
The Meaning of Evolution | Samuel Christian Schmucker
British Dictionary definitions for allantois
/ (ˌælənˈtəʊɪs, əˈlæntɔɪs) /
a membranous sac growing out of the ventral surface of the hind gut of embryonic reptiles, birds, and mammals. It combines with the chorion to form the mammalian placenta
Origin of allantois
1Derived forms of allantois
- allantoic (ˌælənˈtəʊɪk), adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for allantois
[ ə-lăn′tō-ĭs ]
A membranous sac that grows out of the lower end of the alimentary canal in embryos of reptiles, birds, and mammals. In mammals, the blood vessels of the allantois develop into the blood vessels of the umbilical cord.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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