Adolescent Boys

 A near replication in the extent of the testicles and the scrotal sac proclaims the advent of puberty. Fuelled by testosterone, the next changes of puberty come in quick succession. A few light-coloured downy hairs emerge at the base of the penis. A boy may have adult-size genitals as early as age thirteen or as late as eighteen. A child may deliberately masturbate himself to his first ejaculation.