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allantois
[ uh-lan-toh-is, -tois ]
noun
- a vascular, extraembryonic membrane of birds, reptiles, and certain mammals that develops as a sac or diverticulum from the ventral wall of the hindgut.
allantois
/ ˌælənˈtəʊɪs; ˌælənˈtəʊɪk; əˈlæntɔɪs /
noun
- 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
allantois
/ ə-lăn′tō-ĭs /
, Plural allantoides ăl′ən-tō′ĭ-dēz′
- 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.
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Derived Forms
- allantoic, adjective
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Word History and Origins
Origin of allantois1
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Word History and Origins
Origin of allantois1
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Example Sentences
The cavity of the allantois, if developed, vanishes completely.
This bag is called the allantois, and serves as a sort of lung for the developing chick.
It draws its oxygen and throws off its wastes through the instrumentality of the allantois, which covers it over.
The blood vessels of the allantois take in oxygen and give out carbon dioxide through the porous shell.
The allantois of the chick now gains a new development and an altered function.
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