AP PSYCHOLOGY

Detailed explanation-1: -Data synthesis: The yolk sac is the first site of blood-cell production during murine and human ontogeny. Primitive erythroid cells originate in the yolk sac and complete their maturation, including enucleation, in the bloodstream.

Detailed explanation-2: -In the human embryo, the first site of blood formation is the yolk sac. Later in embryonic life, the liver becomes the most important red blood cell-forming organ, but it is soon succeeded by the bone marrow, which in adult life is the only source of both red blood cells and the granulocytes.

Detailed explanation-3: -The yolk sac is responsible for critical biologic functions during early gestation. Before the placenta is formed and can take over, the yolk sac provides nutrition and gas exchange between the mother and the developing embryo.

Detailed explanation-4: -A yolk sac is a structure that develops inside your uterus during early pregnancy. It provides an embryo with nourishment (food). It helps circulate gasses between you and the embryo. The yolk sac also produces cells that turn into important structures, such as the umbilical cord, blood cells and reproductive organs.

Detailed explanation-5: -The yolk sac is formed from hypoblast endoderm and extraembryonic mesoderm. The hypoblast separates from the inner surface of the embryonic disc in early blastocyst stage, forming an endodermal tube within the trophoblast tube. The hypoblast tube is invested with splanchnic mesoderm after its formation and splitting.