Cryptorchidism: The abnormal position of testicles or testicles not descending to the scrotum is called cryptorchidism in medical science. There are two main mechanisms of male infertility caused by cryptorchidism: First, the temperature in the abdominal cavity is higher than that in the scrotum, which affects the development and spermatogenesis of the testes. Since the growth and development of testes and sperm production function are easily affected by temperature, the elevated temperature will affect the normal development of testes and hinder sperm production. The temperature inside the scrotum of normal men is 1~2℃ lower than that inside the abdominal cavity, which is the most suitable temperature for testicular growth and sperm survival, while cryptorchidism is located inside the abdominal cavity, which causes testicular atrophy and sperm birth obstruction due to the increase of local temperature, thus causing infertility. Secondly, unilateral cryptorchidism can interfere with the spermatogenic function of the normal testis on the opposite side. In the past, it was thought that only bilateral cryptorchidism would affect fertility, but in recent years, it has been found that unilateral cryptorchidism can also lead to infertility. Although theoretically speaking, a unilateral testicle can completely replace the function of two testicles, in reality, the side of cryptorchidism can produce anti-sperm antibodies due to the adverse effects of temperature, thus causing the normal testicle to lose the ability to produce sperm, leading to infertility. Second, Chlamydia trachomatis infection Chlamydia trachomatis: is a microorganism between bacteria and virus, and belongs to the STD pathogens. This pathogen can cause male infertility after infecting the male genitourinary system. The reason for this is that infection with Chlamydia trachomatis can increase the number of pus cells in the semen and cause sperm aberrations, as well as inflammation of the testicles, epididymis and vas deferens, which can affect the birth of sperm and cause blockage of the vas deferens. In addition, it can also induce men to produce their own anti-sperm antibodies. Mycoplasma also infects the vas deferens, seminal vesicles and testes, thereby affecting sperm birth and semen quality. It has been observed that mycoplasma can cause infertility through the following links: 1. Interference with sperm motility. Sperm motility is an important function of healthy sperm and is an important indicator of whether sperm can conceive. Mycoplasma infected sperm, often attached to the head and tail of the sperm, so that the entire sperm hung with varying sizes of attachment, resulting in sperm swimming weakness, entangled with each other, resulting in infertility. 2, sperm malformation rate increased. According to clinical observation, the sperm deformity rate can sometimes be as high as 80% in such infertility patients. 3, destruction of spermatogenic cells. There are a large number of spermatogenic cells in the varicose ducts of the testes, which develop and reproduce to form sperm. When mycoplasma enters the testicular varicose duct from the urethra and prostate, it will destroy the sperm cells and make the “sperm factory” produce shoddy products, leading to infertility. Varicose veins of the spermatozoa: they are the abnormal elongation, expansion and tortuosity of the trailing veins in the spermatozoa. The varicose veins of the spermatic cord may not have any clinical symptoms in the early stage, but with the further development of the disease, testicular pain and swelling may gradually appear. Varicocele is a common cause of male infertility. In the case of varicocele, about 50% to 80% of patients have abnormal semen examination, which is manifested by low sperm count, slow activity and abnormal morphology. It is found that the main reasons for infertility caused by varicocele are: 1. Blood stasis in the dilated spermatic vein leads to elevated testicular temperature, which affects the birth of spermatozoa. 2, blood stagnation causes the spermatic vein pressure to increase, and fresh arterial blood cannot enter the testes, causing a lack of oxygen and nutrients in the testes, which affects the development of spermatozoa. 3, When varicocele, the blood from the adrenal vein and renal vein will return to the testicular tissue, so that the local blood contains bioactive substances such as catecholamines, cortisol, 5-hydroxytryptamine and prostaglandins, which can have toxic effects on the testes and thus lead to infertility. 4. varicocele causes damage to the interstitial cells of the testes, reducing the secretion of testosterone and the content of peripheral blood testosterone, which leads to endocrine disorders and interferes with the birth and development of sperm. 5. There are abundant anastomotic branches between the venous systems of the bilateral testes, and they tend to affect the spermatogenic function of the healthy side of the testes. Five, mumps: a survey found that many men’s infertility can often be traced back to a history of mumps as a child. The mumps virus, in addition to in the parotid gland “for mischief”, but also in the human reproductive, nerve and pancreas and other tissues and organs “trouble”. When it attacks the testicles, it can cause inflammation of the testicles, which may be swollen and painful. If these symptoms are the only ones, it is not a big problem. In serious cases, the mumps virus can shrink the testicular tissue, especially when it destroys the sperm production “factory”, the varicocele, thus affecting the birth of sperm. If both testes are invaded by the mumps virus, it can cause lifelong infertility and is difficult to cure. According to statistics, infertility due to testicular failure accounts for about 14% of male infertility, most of which is due to inflammation of the testicles caused by mumps.