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chorion

Translation
chorion
—chorionic, chorial, adj.
/kawr"ee on', kohr"-/, n.
1. Embryol. the outermost of the extraembryonic membranes of land vertebrates, contributing to the formation of the placenta in the placental mammals.
2. Zool. the membrane around the eggs of certain insects, secreted by cells of the ovary.
[1535-45; < NL < Gk chórion membrane enclosing the fetus]

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also called  Serosa,  

      in reptiles, birds, and mammals, the outermost membrane around the embryo. It develops from an outer fold on the surface of the yolk sac. In insects the chorion is the outer shell of the insect egg.

      In vertebrates, the chorion is covered with ectoderm lined with mesoderm (both are germ layers) and is separated from other embryonic membranes by an extraembryonic body cavity, the coelom. In reptiles and birds it fuses with the allantois. In direct contact with the eggshell of reptiles and birds, this chorioallantoic membrane absorbs oxygen through the porous shell from the atmosphere for nourishment of the embryo; it also discharges waste carbon dioxide through the shell.

      In mammals (except marsupials), the chorion develops a rich supply of blood vessels and forms an intimate association with the endometrium (lining) of the female's uterus. Chorion and endometrium together form the placenta, which is the embryo's principal organ of respiration, nutrition, and excretion.

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Universalium. 2010.

  
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  • chorion — * * * chorion [ kɔrjɔ̃ ] n. m. • 1541; gr. khorion 1 ♦ Biol. Membrane extérieure de l embryon des mammifères qui assure un contact intime avec la muqueuse utérine et joue un rôle dans la nutrition de l embryon. 2 ♦ Histol. Couche superficielle,… …   Encyclopédie Universelle

  • Chorion — Cho ri*on, n. [NL., fr. Gr. ?.] 1. (Anat.) (a) The outer membrane which invests the fetus in the womb; also, the similar membrane investing many ova at certain stages of development. (b) The true skin, or cutis. [1913 Webster] 2. (Bot.) The outer …   The Collaborative International Dictionary of English

  • chorion — 1> биол. хорион, яйцевая или наружная оболочка …   Новый большой англо-русский словарь

  • chorion — chorion. См. хорион. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Chorion — Chorion, Haut, die Hülle der Leibesfrucht mit Ausschluß der innersten der Schafhaut (vergl. Amnion, Embryo, Fötus) …   Herders Conversations-Lexikon

  • Chorion — Humaner Embryo in frühem Stadium …   Deutsch Wikipedia

  • Chorion — For the chorion in invertebrate eggs, see Chorion (egg). Chorion Diagram showing earliest observed stage of human embryo …   Wikipedia

  • Chorion — 1.Le chorion, nom grec du placenta, est l enveloppe la plus externe de l œuf. Chez les mammifères, il est en contact avec les tissus maternels. La nature du chorion varie suivant la période de la grossesse. 2.Le chorion définit aussi le tissu… …   Wikipédia en Français

  • Chorion — The outermost of the two fetal membranes—the amnion is the innermost . which together surround the embryo. The chorion develops villi (vascular fingers) and gives rise to the placenta. In Greek, the word "chorion" means "skin… …   Medical dictionary

  • Chorion — Cho|ri|on 〈[ko:r ] n.; s; unz.; Anat.〉 = Zottenhaut [<grch. chorion „Fell“] * * * I Chorion   (Zottenhaut): die mittlere Eihaut des jungen Embryos, mit der dieser sich in der Gebärmutterschleimhaut einnistet und so mit ihr verwächst.   Siehe a …   Universal-Lexikon