he hypothalamus and pituitary gland, which are in the brain, initiate puberty. The hypothalamus secretes luteinizing hormone-releasing hormone, which stimulates the pituitary to secrete luteinizing hormone and follicle-stimulating hormone. Luteinizing hormone causes the testes to produce testosterone. Follicle-stimulating hormone (plus testosterone) causes the testes to produce sperm. Testosterone is responsible for the development of secondary sex characteristics, features that stimulate male development (including characteristics that are not part of the reproductive system, such as facial hair growth and voice change).
