Adolescent development is the stage of transition from childhood to adulthood, when the reproductive organs begin to develop to maturity. When people often talk about puberty, they generally think that it refers to the age of 13 to 19. But in fact, not all children have puberty at the same time, some appear early, some a little later, and there are differences between men and women. Most girls reach puberty between the ages of 10 and 12, while most boys reach it between the ages of 12 and 14. The development of puberty originates in the brain. The hypothalamic-pituitary-gonadal axis in the brain is like a lock that is opened when the body grows to a certain age. One part of the brain, the hypothalamus, produces a chemical called gonadotropin-releasing hormone (GnRH) and transmits it to another part of the brain, the pituitary gland, which secretes two gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH). follicle stimulating hormone (FSH). The gonads start to activate in response to instructions from the hypothalamus and pituitary gland, and puberty begins. Puberty is like a symphony, and the brain is the conductor of the orchestra. Under the coordination of the conductor, each instrument plays at the right time and together they play a beautiful piece of music.