Definition of chorion in English:


Line breaks: chor|ion
Pronunciation: /ˈkɔːrɪən


The outermost membrane surrounding an embryo of a reptile, bird, or mammal. In mammals it contributes to the formation of the placenta.
More 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.


mid 16th century: from Greek khorion.



Pronunciation: /ˌkɒrɪˈɒnɪk/
More 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.

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