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 surface of the chorion is covered evenly with minute villi, constituting a diffuse non-deciduate placenta.

From Project Gutenberg

The villi of the chorion are outgrowths by means of which the very early embryo attaches itself to the walls of the cavity, which it has made for itself in the wall of the uterus.

From Project Gutenberg

The third is the chorion, forming the outer membrane which encloses the fetus, and within which is the amnion, or innermost membrane which surrounds the fetus, and between which is another membrane, called the allantois.

From Project Gutenberg

In the uterus the fetus is surrounded by several membranes which are known as the amnion or inner layer, the allantois or central layer, and the chorion or outer layer.

From Project Gutenberg

Exochorion: that part of the chorion derived from the ectoderm: the outer layer of the chorion.

From Project Gutenberg