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

Etymology: Gk, chorion, skin, sakkos, sack
the saclike membrane that develops from the blastocyst wall to envelop the embryo.

chorionic sac

The outer fetal membrane that encloses the developing embryo.
See also: sac
References in periodicals archive ?
5 weeks, and in all cases when the chorionic sac is at least 8 mm.
The secondary yolk sac is indicated by the first echogenic lines within the chorionic sac.
The chorionic sac should measure about 16 mm; a sac of that size with no heartbeat "is not a good sign," he said.

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