Post Date December, 02 2023
The skin of the scrotum is thin, soft and elastic with sparse and curly pubic hair. Inside is the sperm-producing organ - the testis. Under the scrotal skin, there is a layer of sarcolemma mainly composed of smooth muscle, which contains dense connective tissue and many elastic fibers. There are fibers in the anterior and posterior walls of the sarcolemma extending to the deep layer at the midline and connecting with each other to form a diaphragm. The scrotum is divided into two small pockets on the left and right, containing the left and right testicles and epididymis respectively. There are abundant blood vessels flowing through the sarcolemma, and there are several funnel-shaped fasciae and levator muscle under the sarcolemma, which are mainly composed of the abdominal periosteal aponeurosis and muscle fibers. There is also spermatic cord in the scrotum, which is a round cord-like substance composed of vas deferens, testicular artery, racemose venous plexus, nerve plexus, lymphatic vessel and capsule.
Dark skin: "display" of sex hormone
The skin color of a person depends on the amount of various pigments, especially melanin, the thickness of the skin and the contraction or relaxation of blood vessels. The important factor affecting skin melanosis is sex hormone. For both men and women, the concentration of sex hormones contained in sensitive parts of sexual organs is high, such as nipple and surrounding skin (i.e. areola), scrotum, labia, etc., especially after shrinking and thickening.
If you observe carefully, you may also find that the color of adult men's nipples and the surrounding area is quite black, while the color of juvenile adolescents' nipples and the surrounding area is pink; The scrotum of an adult man is black, while the scrotum of a young boy is similar to the surrounding skin color. This pigmentation will not occur until after puberty.
All these phenomena are due to the fact that these parts are stimulated by sexual hormones for a long time, resulting in a large amount of melanin deposition and deep skin color.
Scrotum, human air conditioning for maintaining spermatogenic environment
The spermatogonia in the testis can produce tens of millions of sperm a day. However, in the warm place of the body, not only the balance of nutrition supply can not be maintained, but also the activity of the reaction enzymes that produce sperm is destroyed. Therefore, if you want to produce mature sperm, you must keep it at a temperature 2~4 ℃ lower than the body temperature. If the temperature is too high, the spermatogenesis will be blocked or even stopped completely; Too low temperature will affect sperm development and survival.
The fold of scrotum just takes on the role of heat dissipation and heating of air conditioning equipment. The scrotal skin is very sensitive to the external temperature. When winter comes, due to the effect of cold air, the smooth muscle of the sarcolemma and the levator muscle of the testis are stimulated to contract, so that the position of the testis is raised, and the scrotum is rapidly compressed into dense folds to prevent heat dissipation and help keep warm. If you just enter the water for swimming, the same phenomenon will occur because the water temperature is lower than the body temperature. After entering the summer, due to the increase of the external temperature, the smooth muscle and the levator muscle stretch to the maximum extent, so as to lower the testicles as far as possible and keep away from the body, the skin of the scrotum is loose, and the density of wrinkles is reduced, thus increasing the heat dissipation area, which is conducive to local heat dissipation. At the same time, the arteries in the spermatic cord are wrapped in bundles of parallel venous plexus. The blood in the two sets of vascular systems flows in reverse direction only across the thin vascular wall, forming a countercurrent exchange system. The venous blood keeps taking away the heat from the arterial blood in the abdominal cavity. As a result, the blood temperature of the testicular artery is lower than that of the abdominal aorta.
Nowadays, many young people like to wear jeans to show the free and unconstrained beauty. However, the crotch of these pants is very tight and the fabric is thick, which is not conducive to heat emission. According to the measurement, the crotch temperature can be as high as 40 ℃. Such a high temperature, even if the scrotum has the function of regulating temperature, will inevitably cause a large number of sperm deaths. If the dead sperm exceeds 50%, it will be difficult to conceive.
The reason why the testicle can be suspended is that it is wrapped by double-layer muscle tissue. The reticular muscle with the levator muscle on the inside wraps the testicle and connects with the abdominal muscle. If you prick the inside of the thigh of a healthy person with a needle, you can see that the testicle is lifting and lowering vigorously, because the levator muscle is flexible, and its movement is controlled by the abdominal muscle.
In fact, the testicles are not suspended when they are loaded into the scrotum from the beginning. When 8 to 10 weeks pregnant, testicular tissue is born near the kidney, growing and falling gradually. Only about 9 months later did it enter the subcutaneous channel at the groin of the thigh root and be included in the scrotum. When some babies are born, their testicles fail to descend normally, which is called cryptorchidism in medicine. If this is the case for a long time, because the temperature of the abdominal cavity is higher than that of the scrotum, the spermatogonia cannot produce sperm, thus affecting the fertility function, so it must be lowered into the scrotum through surgery in childhood.
Not injured by severe pain, protective umbrella for testicular defense reaction
The testicle in the scrotum is a delicate organ that cannot be pinched. In daily life, if our scrotum is suddenly impacted or hit, we will feel pain immediately. This is because the testicle is wrapped with a thin white membrane. Due to the sudden impact or impact, a part of it is stretched instantly, and the nerves on the membrane feel intense pain.
Although the testicular pain response is intense, it will not be easily injured. In many traffic accidents, the victims of penis injuries are often seen, but few of them have testicular injuries. It turns out that the testicles have a defensive response to trauma - once the testicles are aware of danger, they shrink inward, just like turtles shrink their heads into their shells.
Skin shrinkage, a reflection of mood fluctuation
In order to maintain the proper temperature required by the testicles, the scrotum will dissipate heat or keep warm through wrinkles, but the contraction of the scrotal skin cannot be understood in such a simple way. Because heat and cold are not the only factors of scrotal contraction, and the scrotum is not only subject to the command of heat and cold. It is the emotional center or autonomic nerve center inside the brain that commands the scrotum.
Fear, tension, anger and sexual excitement can also make the scrotum shrink - or lift or droop. The contraction of the scrotum truly reflects the psychological activities of men. On the contrary, when a man is depressed and depressed, the scrotum will also appear "listless".
It is said that there was a famous baseball coach who used it to confirm the pitcher's nervousness. He squeezed the pitcher's crotch tightly before the pitcher was in place. If the scrotum shrank, the pitcher would not be sure to throw the ball well. Therefore, scrotal constriction can also be said to be a sign of body tension to some extent.
