The causes of male infertility are very complicated, mainly in the following aspects:
(1) Testicular dysfunction: There are many factors that affect testicular function, resulting in spermatogenesis disorder and infertility. Congenital diseases, such as Creutzfeldt-Jakob disease, have XXY chromosomes, one more X chromosome than normal men. In this kind of patients, the seminiferous tubules are underdeveloped and there is no sperm. Under the influence of high temperature in the body, the development of testicular reproductive epithelium and spermatogenic function are affected, and sperm cannot be produced, resulting in infertility; Endocrine disorders, such as hyperprolactinemia caused by pituitary adenoma, reduce gonadotropin-releasing hormone, affect sperm production and lead to infertility. In addition, varicocele and orchitis, especially parotitis complicated with orchitis, can also cause spermatogenic disorders.
(2) Obstruction of vas deferens: Sperm is transported through epididymal vas deferens and ejaculatory duct. If any part of this link is blocked, obstructive azoospermia will be formed and infertility will occur. If some people are congenital malformation and bilateral vas deferens are missing, some people are infertile because of hernia repair, vas deferens injury, or vas deferens obstruction caused by inflammation and tuberculosis.
(3) Sexual dysfunction: such as impotence, premature ejaculation, non-ejaculation, retrograde ejaculation, and external genital malformations such as too small penis and hypospadias, which make it difficult to have sexual intercourse and cannot transport semen into the vagina, resulting in infertility.
(4) Infection of male accessory gonads: Male accessory gonads are mainly prostate and seminal vesicle, and their secretions are involved in semen components, containing a lot of enzymes and various nutrients, which have an important impact on sperm operation and physiological function. Once the accessory gonad is infected, its function will inevitably decline, and various parameters of semen will change accordingly, such as the decrease of sperm quantity, the decrease of sperm vitality and the increase of sperm deformity rate, which will lead to the decrease of male fertility and even infertility.
(5) Immune factors: Sperm contains a variety of protein, which has a certain chemical structure and antigenicity. When this substance enters men's own blood circulation, it stimulates the immune system to produce antibodies, that is, anti-sperm antibodies. Under normal circumstances, due to the existence of the special structure "blood-testis barrier", the immune system is separated from sperm antigens, so anti-sperm antibodies will not be produced. But when the blood-testis barrier is destroyed by inflammation and trauma, it is possible to produce anti-sperm antibodies. Once sperm comes into contact with anti-sperm antibodies in body fluids (such as seminal plasma), it can agglutinate sperm, prevent sperm from combining with eggs, and lead to infertility.