Approximately 300,000 germ cells migrate to each ridge during embryogenesis, and this number increases up to the time of puberty. After puberty, each spermatogonium that is undergoing differentiation gives rise to sixteen primary spermatocytes, each of which then enters meiosis and gives rise to four spermatids and ultimately four sperm (Fig. 11.13). In the adult male, approximately 100 million sperm are formed each day.
