Which of the following is correct about the precursors of gametes? Primordial germ cells, the earliest recognizable precursors of gametes, arise outside the gonads and migrate into the gonads during early embryonic development. Primordial germ cells first become readily recognizable at 2124 days after fertilization in the endodermal layer of the yolk sac: Germ cells exit from the yolk sac into the hindgut epithelium, and then migrate through the dorsal mesentery until they reach the primggdia of the gonads. During their migration, their number increase significantly through mitosis. All of the above.