Share this entry
chorion Syllabification: cho·ri·on
Pronunciation: /ˈkôrēˌän/

Definition of chorion in English:


The outermost membrane surrounding an embryo of a reptile, bird, or mammal. In mammals (including humans), it contributes to the formation of the placenta.
Example sentences
  • In insects, the genes that encode the proteins of the egg membrane, the chorion, become amplified in the surrounding follicle cells.
  • A needle was used to roll the embryo out of the chorion.
  • Care was exercised not to separate the amniotic sac into its components, the chorion and amnion.


Pronunciation: /ˌkôrēˈänik/
Example sentences
  • Amniotic fluid, chorionic villi, or fetal serum can be tested for evidence of West Nile virus infection.
  • Triple screening should not replace amniocentesis or chorionic villous sampling in pregnancies at high risk for trisomy 21.
  • These authors found ultrastructural evidence of altered endothelial and smooth muscle cells within chorionic vessels exhibiting HEV-like lesions.


Mid 16th century: from Greek khorion.

Definition of chorion in:
Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.

Subscribe to remove ads and access premium resources