Germ cells near the outer wall of the seminiferous tubules of the testis differentiate into stem cells called spermatogonia.

Spermatogonia divide by mitosis, and mature into primary spermatocytes.

Each primary spermatocyte undergoes meiosis:

The spermatids migrate toward the lumen (central opening).

Sertoli cells supply nutrients for the spermatids, which mature into motile sperm in the epididymis.