chorion

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Related to chorions: chorion frondosum, chorion laeve

chorion

 [kor´e-on]
an extraembryonic fetal membrane, composed of trophoblast lined with mesoderm; it develops villi, becomes vascularized, and forms the fetal part of the placenta.
chorion frondo´sum the placental part of the chorion; it is covered by villi.
chorion lae´ve the nonvillous, membranous part of the chorion.

cho·ri·on

(kō'rē-on),
The outermost fetal membrance in human embryos, the villous part of which becomes the fetal part of the placenta.
Synonym(s): membrana serosa (1)
[G. chorion, membrane enclosing the fetus]

chorion

(kôr′ē-ŏn′)
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·on′ic (-ŏn′ĭk) adj.

cho·ri·on

(kōr'ē-on)
The multilayered, outermost fetal membrane consisting of extraembryonic somatic mesoderm, trophoblast, and, on the maternal surface, its villi are bathed by maternal blood; as pregnancy progresses, part of the villous chorion becomes the fetal part of placenta.
Synonym(s): membrana serosa (1) .
[G. chorion, membrane enclosing the fetus]

chorion

The outer of the two membranes that enclose the embryo. The inner is called the amnion.

chorion

  1. the superficial outer coat of the insect egg which is noncellular and secreted by the ovary around the ovum.
  2. an embryonic membrane of AMNIOTES formed from an outer ectodermal layer (see ECTODERM and an inner mesodermal layer (see MESODERM). see AMNION. In birds and mammals it forms the outer membrane covering the amniotic cavity, and in mammals the mesodermal component of the chorion fuses with the allantois to form the chorioallantoic PLACENTA. Here the chorion develops finger-like outgrowths, the chorionic villi, which project into blood spaces in the uterus of the mother. see CHORIONIC BIOPSY.

Chorion

The outermost membrane of the sac enclosing the fetus.
Mentioned in: Prenatal Surgery
References in periodicals archive ?
meditabunda, immediately following emergence from the eggs, visit several eggs/chorions and spend a relatively large amount of time on top of each one before moving off to the side and settling into their final position adjacent the chorions.
Egg mass of Edessa meditabunda showing the nymphs inside the chorions (a); nymph emerging from the corion [circled in red (b)]; nymph on the top of the corion after complete emergence [circled in red(c)]; and nymphs positioned around the chorions and facing them (d).
The T-shaped "take off" sign, formed by the junction of two amnions within one chorion, is a reliable indicator of monochorionic-diamniotic twins in the first trimester.
Fetal membrane specimens were taken from another 18 women with preterm PROM but were excluded from the main analysis because these women lacked a chorion laeve.
Although the amnion was intact in these 16 specimens, "the chorion was destroyed and replaced by inflammatory cells," she said.
"This supports the hypothesis that inflammation accelerates cell death, either by apoptosis or necrosis, and destroys the chorion laeve," Dr.
The pharmaceutical consortium's studies also did not resolve important questions surrounding the presence of the chorion. For example, the uptake studies were generated almost exclusively from pharmaceuticals (17/20 chemicals), raising the question of whether the results are valid for other types of chemicals.
Another laboratory initiates exposure at 24 hpf so that they can identify fish that fail to survive mechanical removal of the chorion.
While the laboratories differ in a number of experimental design parameters, differences in the status of the chorion and exposure frequency are considered the most relevant to study outcome.
The outermost membrane, the chorion, overlays the viscous fluid-filled perivitelline space, the vitelline membrane, and the blastoderm (or embryo) and yolk (Jones et al., 1978; Rawson et al., 2000).