This chapter discusses male reproductive system, which consists of the testes, the accessory glands. The testes are made up of long, thin coiled tubes called seminiferous tubules. Spermatogenesis means the formation of male gametes, called spermatozoa, or simply sperms. The precursors of sperms are the cells called spermatogonia, which line the outer border of seminiferous tubules. The principal hormone directly affecting spermatogenesis is testosterone. Semen is the fluid deposited by the male in the female genital tract. The mucoid nature of the seminal vesicle fluid is responsible for the stickiness of semen. The prostatic fluid contains enzymes for coagulation and also for dissolving the clot. Vaginal secretions improve the motility and fertilizing ability of sperms. Sperms which have undergone capacitation release some hydrolytic enzymes from the acrosome. At puberty there is a sudden increase in testosterone secretion which leads to the development of male secondary sex characteristics in boys.