Which statement about the yolk sac is true?

Question

Quizplus · Accepted Answer

The yolk sac forms during the early stages of embryonic development, not during the third trimester of pregnancy. It is not the outer ring of cells that surrounds the blastocyst (this is the trophoblast). The yolk sac does produce blood cells until the organs are mature enough to take over this function. It contains one large vein and one or two arteries, but their function is to supply and remove blood from the embryo, not specifically loaded with nutrients or waste.

Which Statement About the Yolk Sac Is True