chorion

Definition

The protective and nutritive membrane in higher vertebrates that attaches the fetus to the uterus.

Etymology

From Late Latin chorion, from Ancient Greek χόριον (khórion, “membrane surrounding the fetus, afterbirth”).

Example Sentences

• "2002, Rovert E. A. Stewart, Barbara E. Stewart, Female Reproductive Systems, entry in Encyclopedia of Marine Mammals, page 425, The allantois fuses with the chorion, forming a small round area, the allentochorion. This region becomes the placenta (Fig. 3)."
• "In this illustration, some license is taken, since the amnion is shown as still separate from the chorion; this is done to illustrate the process of apposition of the amniotic sac to the chorion and to accentuate the interposition of the yolk sac between the amnion and the chorion."
• "The amnion and chorion begin to develop soon after fertilization and continue to grow until about 28 weeks′ gestation."