Which of the following structures give origin to the Primordial Germ cells?

Primordial germ cells normally develop from the wall of the yolk sac close to allantois. After folding of the embryo these cells are present in the wall of hindgut. The primordial germ cells then migrate along the dorsal mesentery of hindgut by active ameboid movement and reach the developing gonad. The primordial germ cells get mixed with the sex cords, which are thus composed of two cell types, the cells of coelomic epithelium and primordial germ cells. Here onwards development of testes and ovaries will follow a different path.