Which of the following is NOT a function of the placenta?
- A. Production of the fetus's red blood cells
- B. Exchange of oxygen and carbon dioxide
- C. Secretion of progesterone and hCG
- D. Transfer of nutrients from mother to fetus
Explanation
The fetus makes its own blood cells, first in the yolk sac and liver and later in the bone marrow, and maternal and fetal blood never actually mix in the placenta. What the placenta does is bring the two circulations close enough for exchange of gases, nutrients, wastes and antibodies, and it also works as an endocrine gland from about the third month. It further acts as a partial barrier, though alcohol, nicotine and many viruses cross it.