puberty (pyōō´bərtē), period during which the onset of sexual maturity occurs. It usually takes place between the ages of 10 and 15 in both sexes but sometimes occurs as early as 7 or 8 years of age in females. The pituitary gland secretes hormones that stimulate enlargement and development of the sex organs, which thus become capable of reproduction. The appearance of secondary sex characteristics also occurs during puberty. In females the reproductive cycle of ovulation and menstruation begins, pubic hair appears, and development of the breasts and other body contours takes place. Physical changes in males include production and discharge of semen, appearance of facial and body hair, and deepening of the voice. Skin difficulties, such as acne, may affect both sexes. Puberty, a transition period coinciding with adolescence, involves both physiological and psychological adjustments. It is often marked by emotional stress arising as the adolescent relinquishes childhood behavior patterns and adopts those of an adult.