The normal shape of the testes in an adult male is generally oval, and the weight of the testes is 10-15 g. The testes in a mature male are about 3.5-6 cm long, 2.3-4 cm wide, and 2-2.8 cm thick. The testes are unique to the male, presenting a symmetrical oval sphere, inside the scrotum, one on each side, with a smooth surface, internal convoluted spermatic ducts, and the presence of supporting cells to produce sperm and androgens. For the upper and posterior part of the testis, there are parotesticular cephalic bodies caudal to the attachment in the testis. Normally the upper posterior segment merges with the epididymal head. The testes can move and rotate normally. The testes will gradually atrophy as men get older, especially in the elderly where testicular atrophy is more pronounced. If the testicles suddenly appear painless enlargement, you need to be alert to testicular tumors and other conditions.