Testosterone: Functions and Regulation

Gonadotropin-releasing hormone from the hypothalamus stimulates the pituitary gland to release follicle-stimulating hormone, FSH and luteinizing hormone, LH triggers the production of testosterone.

LH travels through the bloodstream to the testes, stimulating the Leydig cells to produce and release testosterone.

LH and FSH stimulate the Sertoli cells to release androgen-binding protein around the spermatogenic cells, binding testosterone and increasing its concentration for spermatogenesis.

Testosterone drives the prenatal development of male internal reproductive structures, such as differentiation of the Wolffian ducts into seminal vesicles and vas deferens, as well as the external genitalia, while the testes develop independently. During puberty, testosterone promotes the growth and maturation of the testes and supports the development of secondary sexual characteristics in males, including facial hair, a deeper voice, increased muscle mass, and heightened libido.

When testosterone levels in the blood are high, they inhibit the release of gonadotropin-releasing hormone, FSH, and LH, creating a negative feedback loop to reduce testosterone production. Inhibin, produced by Sertoli cells, also suppresses FSH to regulate spermatogenesis.