Which structure is formed from both uterine tissue and embryonic tissue and functions as the site of nutrient and gas exchange?

Which structure is formed from both uterine tissue and embryonic tissue and functions as the site of nutrient and gas exchange?

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

Answer: (C)

The placenta forms from both maternal tissue in the uterus (the decidua basalis) and embryonic tissue (the chorion with its villi), creating the organ that links mother and fetus. In this structure, chorionic villi grow into the maternal tissue and bathe in the maternal blood in the intervillous spaces, establishing a large surface area for exchange. Nutrients and oxygen diffuse from the mother’s blood into the fetal blood, while carbon dioxide and waste products diffuse in the opposite direction. The maternal and fetal blood do not mix; they stay separate across a specialized placental barrier that regulates exchange. Other structures aren’t the site of this nutrient and gas exchange: the chorion is an embryonic membrane involved in forming the placenta, the amnion is a protective sac around the embryo, and the umbilical cord is the conduit containing vessels that transport substances between fetus and placenta.

The placenta forms from both maternal tissue in the uterus (the decidua basalis) and embryonic tissue (the chorion with its villi), creating the organ that links mother and fetus. In this structure, chorionic villi grow into the maternal tissue and bathe in the maternal blood in the intervillous spaces, establishing a large surface area for exchange. Nutrients and oxygen diffuse from the mother’s blood into the fetal blood, while carbon dioxide and waste products diffuse in the opposite direction. The maternal and fetal blood do not mix; they stay separate across a specialized placental barrier that regulates exchange. Other structures aren’t the site of this nutrient and gas exchange: the chorion is an embryonic membrane involved in forming the placenta, the amnion is a protective sac around the embryo, and the umbilical cord is the conduit containing vessels that transport substances between fetus and placenta.