What organ does the developing embryo produce as a site of exchange between maternal and fetal blood?

The correct answer is the placenta, which is a vital organ that forms during pregnancy and serves as the primary site of exchange between the maternal and fetal blood. The placenta facilitates the transfer of essential nutrients, oxygen, and antibodies from the mother to the developing fetus while also allowing for the removal of waste products such as carbon dioxide and urea from the fetal bloodstream. It functions through a complex network of blood vessels and is highly vascularized, ensuring efficient exchange due to the close proximity of maternal and fetal blood supplies without them directly mixing.

In addition to its role in nutrient and gas exchange, the placenta also produces hormones that are critical for maintaining the pregnancy and supporting fetal development. It acts as a protective barrier, offering some degree of immunity to the fetus.

Other options, while related to pregnancy and fetal development, do not play the same critical role in the exchange of materials between maternal and fetal blood. The umbilical cord connects the fetus to the placenta but does not itself function as an exchange site. The chorion is a membrane that contributes to the formation of the placenta and plays a role in implantation, but it is not the site of exchange. The amnion surrounds the amniotic fluid, providing cushioning for the fetus but does not