Primary sexual characteristics

The dramatic hormonal changes associated with puberty lead to the development of the primary and secondary sexual characteristics. Primary sexual characteristics are the maturation of the organs and structures related to reproduction.

For boys this includes growth of the penis and testes and the accessory glands such as the prostate gland that produce most of the fluid within semen. Spermatogenesis, or the production of spermatozoa begins in the testes and boys become able to ejaculate semen.

For girls this includes growth of the uterus and ovaries and the commencement of monthly menstrual cycles that involves ovulation, build up of the uterine wall and its subsequent loss at the end of the cycle.