biology-early development?

Question

Why doesn't the mother's immune system destroy the developing embryo since it is foreign to the body?

A. Because there are no immune cells present in the uterus.

B. Because the mother's genes are being expressed by the embryo and "look" normal to the immune system.

C. Because the developing embryo secretes chemicals which suppress the mother's immune system in the uterus.

D. Because the developing embryo is covered by a thick membrane.

Answer 1

A, C, are partially correct, B and D are incorrect. B: The mother's histocompatibility genes are indeed expressed on the embryo but so are the father genes. The mother's lymphocytes can certainly react to the cells that express both the father's and her own genes (F1). Thus, the mother's immune system must be carefully controlled. D: The membrane mentioned in D might be the yolk sac which has little activity in preventing the influx of immune system cells. A: The placenta lets in only carefully selected cells. Most immune system cells are excluded. C: The pregnant female has high levels of estrogen which suppressed the immune system. Estrogen and other pregnancies hormones are induced by the embryo through a complicated cascade of interactions.

hope that helps
lolal

Answer 2

B.Mother`s genes and father`s genes are expressed. If the child inherits foreign genes of father congenital hemolytic anemia can occur.

Answer 3

B