Stages of spermatogenesis involve certain cell types entering different processes, such as the primary spermatocyte which uses meiosis I, two secondary spermatocytes that use meiosis II, or four spermatids using spermiogenesis.
The primary spermatocyte divides meiotically (Meiosis I) into two secondary spermatocytes; each secondary spermatocyte divides into two equal haploid spermatids by Meiosis II. The spermatids are transformed into spermatozoa (sperm) by the process of spermiogenesis. The entire process of spermatogenesis can be broken up into several distinct stages, each corresponding to a particular type of cell in humans. 
