the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)
any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus
Cite this entry
Style:
MLA
MLA
APA
Chicago
Copy citation
DISCLAIMER: These example sentences appear in various news sources and books to reflect the usage of the word ‘allantois'.
Views expressed in the examples do not represent the opinion of Vocabulary.com or its editors.
Send us feedback
Word Family
2 million people are mastering new words.Master a word
Sign up now (it’s free!)
Whether you’re a teacher or a learner, Vocabulary.com can put you or your class on the path to systematic vocabulary improvement.