Problems with the male reproductive system can occur at various stages of fetal and pubertal development or arise later in life due to accidents, metabolic disease or infection.
Abnormal Development of the Male Reproductive System
Problems with the male reproductive system can arise at conception if a male child receives an extra X chromosome (XXY) resulting in a condition known as Klinefelter's syndrome. This syndrome causes abnormal gonadal development with inadequate testosterone production to support development of male traits such as robust musculature and facial hair. Klinefelter's syndrome is often associated with feminization and infertility. The absence of a gene can also cause abnormalities in the male reproductive system. For instance, mutation or deletion of the SRY gene results in a failure to form testicles, resulting in the development of an ovary and female characteristics in a genetically male child. A condition called congenital absence of the vas deferens is a congenital defect in which the part of the ejaculatory duct (the vas deferens) failed to form so although sperm is produced, sperm can't be ejaculated.
Primary Hypogonadism
Testosterone produced by the testicles is the primary hormone responsible for normal function of the male reproductive system. Reduced functioning of the testicles due to a problem in the testicles themselves is called primary hypogonadism. For instance, the testicles must descend from the pelvis into the scrotum for normal function. Undescended testicles are exposed to higher internal body temperatures which inhibit normal testicular functions, reducing production of both testosterone and sperm. Trauma to the testicles from a sports injury or infections such as mumps or sexually transmitted diseases can directly damage the testicles, resulting in low testosterone levels. Exposure to chemotherapy and radiation cancer damage disrupts testosterone and sperm production, at least temporarily. Normal aging is also associated with decreased testicular function.
Secondary Hypogonadism
Two regions of the brain (hypothalmus and pituitary gland) signal the testicles to produce testosterone in a two-step process. The hypothalmus produces gonadotropin releasing hormone (GNRH) which signals the pituitary gland to produce luteinizing hormone (LH) which in turn, triggers the testicles to produce testosterone. Reduced function of the testicles due to problems with the signaling pathways are classified as secondary hypogonadism because the testicles themselves are able to function normally. Kallmann syndrome results from abnormal development of the hypothalmus which prevents normal testicular function due to disruption of this signalling pathway. Likewise, tumors in the pituitary gland may disrupt testosterone production by preventing signals to the testicles. Some inflammatory diseases such as sarcoidosis, histiocytosis and tuberculosis can impair normal hypothalmic function also. Opiates and other medications which affect the hypothalmus can also indirectly interfere with normal testicular function.
Problems with Sperm Production
The second major function of the testicles is to produce sperm. Semen analysis can detect problems with the quantity and quality of sperm production. The absence of sperm (azoospermia) or low numbers (oligospermia) in the ejaculate are likely to cause infertility or increase the time to conception. Sometimes the quantity of sperm produced may be normal but the number of abnormally shaped sperm may be excessive or sperm may be unable to swim or swim weakly, making fertilization of the egg impossible. These abnormal semen parameters can be caused by testicular damage arising from accidental trauma or infection with bacteria or viruses.
Sexual Dysfunction
Various components of the male reproductive system must work in synchrony for normal sexual function. Problems with sexual dysfunction arise from problems with either libido, erection, ejaculation or orgasm. Problems with sexual desire (libido) may arise from low testosterone levels, clinical depression or side effects of drugs that act on the central nervous system. Problems with erection can arise from problems with the cardiovascular and nervous systems because the brain signals the penis to restrict the blood flow leaving the veins of the penis, causing penile tissue to inflate with blood and become erect. Common conditions that can cause erectile dysfunction are atherosclerosis and diabetes, which are associated with vascular problems. Sometimes erectile dysfunction has a psychological cause such as emotional stress or performance anxiety. Complications from prostate surgery or spinal nerve damage can also cause problems with ejaculation and ability to achieve an orgasm.
