What is the secondary sexual characteristic?

Boys who enter adolescence grow up rapidly under the action of sex hormones. The average height increases by about 6-8 cm every year, the bones and muscles become thick and broad, the voice becomes deep, pubic hair and armpit hair grow in the genitals and armpits, and the beard grows gradually. These are the secondary sexual characteristics of men.

The development of male genitalia in adolescence usually begins at the age of 12. During this period, the testicles and scrotum began to enlarge, the color of the scrotum gradually deepened, and thick pubic hair gradually grew. The average age is about 3 years, and the penis grows and its diameter increases until its sexual development is mature.

In addition to the appearance of the above-mentioned secondary sexual characteristics, the main physiological change in adolescence lies in the maturity of the reproductive system. At this time, the testis began to "make" sperm and secrete androgen. From this time on, boys began to have nocturnal emission, sexual desire and fertility, and became real men.