Fig. 7.

Our model of two-step oligoclonal development of testis germ cells. Male germline starts from four cells. They proliferate, migrate, and split to bilateral genital ridges. However, germ cells actually contributing adult spermatogenesis during the reproductive period originate from a small number of a second founder population that initially seed onto genital ridges. The rest of the germ cells (deciduous germ cells) are removed, most likely by apoptosis, before the reproductive period. Reproduced with permission from ref. 13.