chorionic sac


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Related to chorionic sac: Chorionic villi, extraembryonic mesoderm

chorionic sac

[TE]
the outermost fetal membrane in human embryos, the villous part of which becomes the fetal part of the placenta.
Synonym(s): chorionic vesicle

chorionic sac

The outer fetal membrane that encloses the developing embryo.
See also: sac
References in periodicals archive ?
(The chorionic sac is sometimes called the gestational sac, but the latter term applies only to pregnancies after the amnion fuses with the chorion later in the first trimester, Dr.
A chorionic sac that is smaller than 5 mm at 5 weeks' gestation could be the first sign of abnormal gestational development.
By week 5 or in women with an HCG level of 1,200 mIU/mL, the chorionic sac should be visible in 95% of cases.
The secondary yolk sac can be seen in 50% of intrauterine pregnancies at 5 weeks' gestation, in 95% by 5.5 weeks, and in all cases when the chorionic sac is at least 8 mm.

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