The testis in the scrotum is a "factory" for producing sperm, and the spermatogonia in the testis can produce tens of millions of sperm a day. Temperature is an important condition in the process of sperm production. In order to produce mature sperm, the temperature in the scrotum must be kept 2~4℃ lower than the body temperature. Excessive temperature will hinder spermatogenesis or even stop it completely; On the other hand, if the temperature is too low, it will affect the development and survival of sperm.
The skin folds of scrotum properly shoulder the "heavy responsibility" of air conditioning to dissipate heat and heat, and are extremely sensitive to changes in external temperature. When the temperature drops, the smooth muscle and cremaster muscle in the scrotum contract, which makes the testis rise, and the scrotum contract rapidly or shrink tightly, which is beneficial to heat preservation; When the temperature rises, the smooth muscle and testis catcher will stretch to the maximum extent, so that the testis will descend away from the body, the scrotum skin will relax, the wrinkle density will decrease, and the heat dissipation area will increase, which is beneficial to heat dissipation. It is through this adjustment that the internal temperature of scrotum is 65438 0.5 ~ 2℃ lower than that of abdominal cavity, which is beneficial to the growth and development of sperm.
Careful observation shows that the scrotum skin of adult men is dark, while the scrotum of little boys is similar to the surrounding skin color. The scrotum does not appear pigmentation until after puberty. All these phenomena are due to the long-term stimulation of these parts by sex hormones, which leads to a large amount of melanin deposition and darker skin color. No wonder some people say that scrotal skin color is a "monitor" of sex hormones.
As mentioned above, in order to maintain the proper temperature of the testis, the scrotum will be folded to achieve the purpose of heat dissipation and warmth. But the atrophy of scrotal skin can't be explained so simply. Because cold and heat are not the only factors of scrotal contraction. It is believed that the emotional center inside the brain gives orders to the scrotum. Scrotal contraction can be said to be a "barometer" of mood swings to some extent.
Through careful observation, the researchers found that when men are in emotional fluctuations (such as tension, anger, fear or sexual excitement), the scrotum will also have a strange contraction phenomenon: lifting up or sagging down. On the contrary, when men are depressed and unhappy, the scrotum will also become "listless" and "depressed". This contraction of scrotum can reflect the psychological activities of men.