In higher animals like humans, spermatogonia proliferate by mitosis. Some of the spermatogonia mature into primary spermatocytes. Some of the primary spermatocytes undergo meiosis I to produce haploid secondary spermatocytes. Two secondary spermatocytes are produced per primary spermatocyte. The haploid secondary spermatocytes divide by meiosis II to produce two spermatids. Each secondary spermatocyte produces two spermatids. Thus, a total of four spermatids are produced per primary spermatocyte.