Pole cells constitute the germ line for the next generation.
In males, germ line stem cells, which will eventually locate to the larval testis, are the precursors of the sperm. The genital disc , a structure derived from three abdominal segments, gives rise to the somatic cells of the testis. As larval development in the male begins, so too does the process of spermatogenesis . This condition remains unchanged for the larval testis until shortly before pupation. The differentiation of cells from both germ line and somatic origin are required for spermatogenesis.