Androgens are hormones that promote the maturation of the male sex organs and the appearance of secondary sexual characteristics, as well as maintain normal libido and reproductive function. Androgens are mainly testosterone secreted by the testes, which is a steroid hormone. The testes of adult men secrete about 4mg-9mg of testosterone per day. Testosterone is inactivated in the liver and the inactivated derivatives are excreted through urine. The effects of androgens appear in fetal life. Testosterone in androgens can promote the differentiation of gonadal structures, and male internal and external genitalia are formed under its action. On the contrary, if there is a lack of testosterone or insufficient amount of testosterone in the fetal body, the fetal sexual organs will be deformed or underdeveloped, such as cryptorchidism.