Which structure serves as the link between mother and embryo and forms from both maternal and embryonic tissues?

Which structure serves as the link between mother and embryo and forms from both maternal and embryonic tissues?

• A. Umbilical cord
• B. Amnion
• C. Chorion
• D. Placenta

Answer: (D)

The placenta acts as the interface between mother and embryo, forming from a combination of maternal and embryonic tissues. It develops from embryonic chorionic tissue (trophoblast) that invades the maternal endometrium (decidua) and creates the placental villi, which are bathed in maternal blood. This arrangement allows the exchange of nutrients, oxygen, and wastes while keeping the two blood streams separate. The umbilical cord links the embryo to the placenta, but the cord itself is mainly fetal tissue; the amnion is a separate embryonic membrane, and the chorion helps form the placenta but is not the exchange organ on its own.

The placenta acts as the interface between mother and embryo, forming from a combination of maternal and embryonic tissues. It develops from embryonic chorionic tissue (trophoblast) that invades the maternal endometrium (decidua) and creates the placental villi, which are bathed in maternal blood. This arrangement allows the exchange of nutrients, oxygen, and wastes while keeping the two blood streams separate. The umbilical cord links the embryo to the placenta, but the cord itself is mainly fetal tissue; the amnion is a separate embryonic membrane, and the chorion helps form the placenta but is not the exchange organ on its own.