[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.

Nearby words

  1. choric,
  2. chorine,
  3. chorio-,
  4. chorioadenoma,
  5. chorioadenoma destruens,
  6. chorioamnionitis,
  7. chorioangioma,
  8. chorioangiosis,
  9. choriocapillaris,
  10. choriocapillary layer

Origin of chorioallantois

First recorded in 1930–35

Also called chorioallantoic membrane.

Related formscho·ri·o·al·lan·to·ic [‐al-uh n-toh-ik] /‐ˌæl ənˈtoʊ ɪk/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Medicine definitions for chorioallantois




The highly vascular extraembryonic membrane formed by the fusion of the allantois with the chorion that constitutes the placenta in most mammals.
Related formscho′ri•o•al′lan•toic (-ō-ăl′ən-tōĭk) adj.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.