sexhormone

Sex hormones are chemical messengers that regulate the development of sexual characteristics and the physiology of the reproductive system, as well as various other body processes. In humans and many other animals, the term typically refers to the steroid hormones produced mainly by the gonads—testes in males and ovaries in females—and to a lesser extent by the adrenal glands and placenta during pregnancy.

The principal sex hormones are estrogens (e.g., estradiol, estrone), androgens (e.g., testosterone, dihydrotestosterone), and progestogens (e.g., progesterone). Estrogens and progestogens predominate in females and androgens in males, though both sexes produce each class in varying amounts. These hormones arise from cholesterol and act by binding to specific receptors to regulate gene expression and cellular function.

Functions include the development and maintenance of sexual organs and secondary sexual characteristics, regulation of the menstrual cycle and spermatogenesis, and preparation of the uterus for pregnancy. They also influence bone density, metabolism, cardiovascular function, mood, and cognition, with effects that extend beyond reproduction.

Regulation involves the hypothalamic-pituitary-gonadal axis. Gonadotropin-releasing hormone from the hypothalamus stimulates the pituitary to release luteinizing hormone and follicle-stimulating hormone, which act on the gonads to produce sex hormones. Levels are subject to feedback control and vary with age, sex, circadian rhythms, and physiological states such as pregnancy.

Clinical relevance includes conditions of excess or deficiency, infertility, and the use of hormone therapies. Treatments may involve hormone replacement, contraception, or selective receptor modulators. Measuring sex hormone levels is common in medical assessment and in the investigation of reproductive and metabolic disorders.