The testes (plural for testis) are two oval-shaped glands that are a key component of the male reproductive system. They are located within the scrotum, a sac of skin suspended behind the penis. The primary functions of the testes are to produce and store sperm. Additionally, they are responsible for synthesizing testosterone, a vital hormone that drives the development of male secondary sexual characteristics, including facial hair growth, increased muscle mass, and sexual drive (libido). The processes of sperm formation (spermatogenesis) and testosterone secretion are precisely regulated by the follicle-stimulating hormone (FSH) and luteinizing hormone (LH), both released by the pituitary gland.