As curious as girls are about their own bodies, they also naturally wonder about how boys develop during puberty. For boys, changes typically take place in the following order:
• Genital development. At about age 12, but as early as 9, a boy’s testicles and scrotum gradually begin to enlarge. Then the penis grows.
• Pubic hair. Pubic hair generally appears once genital development is under way. The growth of facial, underarm, and chest hair typically follows.
• Growth spurt. It’s not unusual for boys between the ages of 12 and 16 to shoot up two to five inches in one year. Boys’ muscles develop during the growth spurt as well.
• Ejaculation. A boy experiences ejaculation, the release of semen from the penis, for the first time during puberty.
• Voice change. A boy’s voice deepens during puberty, and for a period of time (usually only a few months but occasionally a couple of years), it may change pitch suddenly, or “crack.” Boys may find this embarrassing, but for some it’s just a normal part of puberty.
You may want to educate your daughter about the male reproductive system. As you discuss the male reproductive organs described below, refer to the diagram on this page.
Outside the body. The most familiar function of the penis is the elimination of urine, the body’s liquid waste. Urine comes from the bladder and passes to the outside of the body through the urethra, which opens at the tip of the penis. (Solid waste is eliminated through the anus.) An erection occurs when blood rushes to the penis, making it stiff so that it stands away from the body.
Below the penis is a sack of skin, the scrotum, which holds the testicles or testes. During puberty, these round glands begin to produce the hormone testosterone. They also produce sperm, male reproductive cells. It is important for young people to realize that when a sperm cell joins with an egg, the result is a pregnancy. Once a boy is able to produce sperm, he is physically capable of fathering a child. Semen, a fluid that contains sperm, leaves the body through the penis. A special valve inside the body prevents urine and semen from passing through the urethra at the same time.
Because sperm need a lower temperature to mature, the testicles are outside the body and stay cooler than normal body temperature.
Internal reproductive organs. The vas deferens are long, thin tubes that carry sperm from the testicles to the seminal vesicles and the prostate gland. These glands secrete fluids that combine with sperm to make up semen.