chorion

American  

[kawr-ee-on, kohr-] / ˈkɔr iˌɒn, ˈkoʊr- /

noun

1. Embryology. the outermost of the extraembryonic membranes of land vertebrates, contributing to the formation of the placenta in the placental mammals.

2. Zoology. the membrane around the eggs of certain insects, secreted by cells of the ovary.

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chorion British  

/ ˈkɔːrɪən /

noun

1. the outer of two membranes that form a sac around the embryonic reptile, bird, or mammal: contributes to the placenta in mammals See also amnion

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chorion Scientific  

/ kôr′ē-ŏn′ /

1. The outer membrane that encloses the embryo of a reptile, bird, or mammal. In mammals, the chorion contributes to the development of the placenta.

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Other Word Forms

Derived Forms

• chorial
  adjective
• chorionic
  adjective
• subchorionic
  adjective

Etymology

Origin of chorion

1535–45; < New Latin < Greek chórion membrane enclosing the fetus

Example Sentences

The chorion facilitates exchange of oxygen and carbon dioxide between the embryo and the egg’s external environment.

From Textbooks • Jan. 1, 2015

Some grow to form the extra-embryonic membranes needed to support and protect the growing embryo: the amnion, the yolk sac, the allantois, and the chorion.

From Textbooks • Jun. 19, 2013

Four embryonic membranes form to support the growing embryo: the amnion, the yolk sac, the allantois, and the chorion.

From Textbooks • Jun. 19, 2013

These form the chorionic membrane, which envelops the entire conceptus as the chorion.

From Textbooks • Jun. 19, 2013

The one layer of the allantois is spread over the outer surface of the amnion and the other over the inner surface of chorion.

From Special Report on Diseases of Cattle by United States. Bureau of Animal Industry