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

• 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

The mechanism of gas exchange at the chorion is similar to gas exchange at the respiratory membrane.

From Textbooks • Jun. 19, 2013

The chorionic villi of the chorion extend into the endometrium to form the fetal portion of the placenta.

From Textbooks • Jun. 19, 2013

Blood cells and vessel production in structures outside the embryo proper called the yolk sac, chorion, and connecting stalk begin about 15 to 16 days following fertilization.

From Textbooks • Jun. 19, 2013

The umbilical cord goes from its navel to the placenta. b amnion, c chorion, d placenta, d apostrophe, relics of villi on smooth chorion, f internal or reflex decidua, g external or true decidua.

From The Evolution of Man — Volume 1 by Haeckel, Ernst Heinrich Philipp August