The testes (testicles) are the male gonads – two oval-shaped organs housed in the scrotum. They have two main functions: producing sperm (spermatogenesis) and secreting testosterone and other male hormones.
Hormone Production:
Leydig cells in the testes produce testosterone in response to luteinizing hormone (LH) from the pituitary gland. Testosterone production begins during fetal development, surges during puberty causing male sexual characteristics, and continues throughout life, though levels gradually decline with age.
What Testosterone Does:
Testosterone from the testes is responsible for development of male reproductive organs, sperm production, development of male secondary sexual characteristics during puberty (deepening voice, facial hair, muscle development), maintenance of muscle mass and bone density, sex drive and erectile function, and influences mood and energy levels.
The Feedback Loop:
Testosterone production is controlled by the HPG (Hypothalamic-Pituitary-Gonadal) axis. The hypothalamus releases GnRH, signaling the pituitary to release LH and FSH. LH stimulates testosterone production while FSH (along with testosterone) stimulates sperm production. When testosterone levels are adequate, it signals back to reduce GnRH and LH release.
