Fetus (d20-40)
Germ cell division and differentiation
Fetus (d 60 ++)
Testicular dissension from the abdomen into the scrotum
1-2 months
Mounting behavior displayed
3 months
2nd germ cell division and increase in testes to body weight ratio
4 months
Sperm appear in seminiferoustubules and erections can occur
5.5months
Puberty begins and sperm appear in ejaculate
6-18 months
Testes size, semen concentration and ejaculate volume increases