chorion /cho·ri·on/ (kor´e-on)
Chorion
chorion
1. in human embryology, the cellular, outermost extraembryonic membrane, composed of trophoblast lined with mesoderm; it develops villi, becomes vascularized by allantoic vessels, and forms the fetal part of the placenta.
2. in mammalian embryology, the cellular, outer extraembryonic membrane, not necessarily developing villi.
3. in biology, the noncellular membrane covering eggs of various animals; e.g., fish and insects.chorion´ic
chorion frondo´sum the part of chorion bearing villi.
chorion lae´ve the nonvillous, membranous part of the chorion.
shaggy chorion , villous chorion c. frondosum.
cho·ri·on (kôr  - n )n. The outer membrane enclosing the embryo in reptiles, birds, and mammals. In placental mammals it contributes to the development of the placenta. cho ri·onic (-n k) adj. |
Chorion
The outermost membrane of the sac enclosing the fetus.
Mentioned in: Prenatal Surgery
chorion
[kôr′ē·on]
Etymology: Gk, chorion, skin
the outermost extraembryonic membrane composed of trophoblast lined with mesoderm. It develops villi about 2 weeks after fertilization and is vascularized by allantoic vessels 1 week later. It gives rise to the placenta and persists until birth as the outer of the two layers of membrane containing the amniotic fluid and the fetus. Compare amnion. See also amniotic sac.
chorion
the outermost of the fetal membranes, composed of trophoblast lined with mesoderm; it develops villi, becomes vascularized by allantoic vessels, and forms the fetal part of the placenta.
chorion frondosum
the part of the chorion covered by villi.
chorion laeve
the nonvillous, membranous part of the chorion.
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