Final answer:
Puberty in males is initiated by the hypothalamus triggering the release of FSH and LH, which stimulate the production of testosterone in the testes. Testosterone causes the development of secondary sexual characteristics and the growth of genitalia.
Step-by-step explanation:
Puberty in males is triggered by a sequence of hormonal actions that originate in the brain. The hypothalamus signals the pituitary gland by secreting gonadotropin-releasing hormone (GnRH), which in turn releases two other hormones into the bloodstream: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH travel to the testes, where LH stimulates the Leydig cells to produce and release testosterone. Testosterone is crucial for the onset of puberty, driving the development of secondary sexual characteristics like the growth of facial, axillary, and pubic hair, as well as the deepening of the voice. It also stimulates spermatogenesis and the growth of sex organs like the testes.
Testosterone, therefore, is the hormone responsible for the physical changes in the male body during puberty, including increased muscle bulk and the beginnings of the sex drive. This period of rapid development typically begins between the ages of 11 and 13 and can continue into the early 20s.