Puberty and its disorders

Puberty is the stage of growth leading to sexual maturity and reproductive capacity. In girls, the initial physical changes are breast development; in boys, testicular growth-both consequences of increased gonadotropin and sex steroid secretion. The progressive physical changes seen in breast, genitals, and pubic hair are described using the Tanner staging system that breaks the continuous pubertal physical changes into one of five stages. Accelerated growth begins at the onset of puberty in girls and at mid-puberty in boys. Menstruation and spermatogenesis also begin mid to late puberty. Gonadotropins [luteinizing hormone (LH) and follicle-stimulating hormone (FSH)] both stimulate the synthesis of estradiol in the ovary, which in turn stimulates breast and reproductive system maturity in females. LH stimulates testosterone synthesis by the testicular Leydig cells, while FSH stimulates seminiferous tubule maturation. Androgen stimulates pubic and axillary hair development, apocrine gland maturation resulting in adult-type body odor, and skin changes related to acne. Sex steroids stimulate overall somatic growth directly and indirectly via increased growth hormone secretion. Estradiol is the key hormone stimulating skeletal maturity in both sexes.