fetal membrane

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Fetal membrane

One of the membranous structures which surround the embryo during its developmental period. Since such membranes are external to the embryo proper, they are called extraembryonic membranes. They function in the embryo's protection, nutrition, respiration, and excretion.

There are four fetal membranes—the amnion, chorion, yolk sac, and allantois. In the course of development, the chorion becomes the outermost, and the amnion the innermost, membrane surrounding the developing embryo. As the allantois increases in size, it expands and becomes closely associated, if not fused, with the chorion. The two membranes together are known as the chorioallantoic membrane.

The amniotic cavity within which the embryo is enclosed becomes filled with an aqueous fluid which gives osmotic and physical protection to the embryo during the remainder of its fetal existence. Smooth muscle fibers in the amnion spontaneously contract and gently rock the embryo before it develops the capacity for spontaneous movement.

As the stored nutrients of the yolk are depleted during development, the yolk sac gradually decreases in size and is eventually incorporated into the midgut of the embryo. The yolk sac in the nonyolky eggs of placental mammals is vestigial. It has evolutionary but essentially no functional significance.

At the time of birth or hatching, the embryo becomes completely separated from the amnion and chorion and from the major portion of the allantois. The proximal portion of the latter remains within the embryo, however, as the urinary bladder. See Allantois, Amnion, Chorion, Yolk sac

fetal membrane

[′fēd·əl ′mem‚brān]
Any one of the membranous structures which surround the embryo during its development period. Also known as extraembryonic membrane.
References in periodicals archive ?
have demonstrated the presence of considerable amounts of this immunoglobulin in chorioamniotic membranes of women with premature rupture of fetal membrane (16).
His group is collaborating with researchers in Europe to conduct in-vivo testing of their mussel-inspired medical sealants for fetal membrane repair.
As mentioned in an earlier section of this chapter, the fetal membranes do not invade the endometrial mucosa in swine, sheep, cattle, and horses.
The differentiation of organs and the growth and structure of the placenta, fetal membranes, uterus, and the fetus itself are described.
A second expert had stated that the only reasonable cause for the rupture of her fetal membrane was illness from the S.
Duration of antibiotic therapyafter preterm premature rupture of fetal membranes.
The fetal membranes identified were chorium, applied on the uterine surface and, amnion adherent to inner face of chorium.
The fetal membrane is the structure that surrounds the developing fetus.
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.
Fetal membranes, premature rupture; labor, premature; pregnancy complications; gestational age.
1994) recorded that ergometrine injection upto 12 hrs postpartum in cows reduced Retention of fetal membrane (RFM), reduced incidence of endometritis and improved reproductive efficiency.
Identification of risk factors and peripartum metabollic indicators for retention of fetal membrane in bovine.