Question

The _________ is the site of the _________ which is the first site of hematopoiesis in the developing embryo.
a. cardiogenic mesoderm, liver
b. bone marrow, blood islands
c. ectoderm, blood islands
d. yolk sac, blood islands

Answer 1

Answer: D

Explanation:

During embryogenesis, hematopoiesis begins in week 3 in the Yolk Sac, in Pander´s Island or Wolff´s Island, commonly known as the "blood islands". These blood islands develop from the umbilical vesicle, allantois, and chorion. In week 5, blood production starts on the fetal liver, and finally, at week 12 it begins in the bone marrow, spleen and, thymus.