The maternal contribution to the placenta is the
A)decidua basalis.
B)chorion frondosum.
C)chorionic villi.
D)yolk sac.

Question

Quizplus · Accepted Answer

The decidua basalis is the maternal contribution to the placenta. It is the part of the endometrium that lies directly beneath the blastocyst and forms the maternal-fetal interface. The other options are all fetal contributions to the placenta. The chorion frondosum is the outer membrane of the fetal sac that surrounds the embryo and gives rise to the placenta. The chorionic villi are finger-like projections on the chorion frondosum that help exchange nutrients and waste between mother and fetus. The yolk sac is an embryonic membrane that helps in early blood cell formation and nutrient transfer, but it does not contribute to the placenta.

The Maternal Contribution to the Placenta Is the