As with female reproduction, male reproduction is hormonally driven, requiring a normally functioning hypothalamus and pituitary gland. As in women, gonadotropin releasing hormone, or GnRH, is released in a pulsatile fashion, stimulating the release of follicle stimulating hormone (FSH) and leutinizing hormone (LH). In men, LH primarily stimulates testosterone production, while FSH stimulates the production of sperm. The testes must be capable of response to this hormonal stimulus. In addition, there must be an intact ductal system to transport sperm to the urethra.
The male external genitals consist of the scrotum, which houses the testes and associated ductal systems (the epididymis and vas deferens), and the penis. The testes are covered by a tough fibrous layer called the tunica albuginea, which divides the testes into lobules. Each of the 200 to 300 lobules contains one to three long and tightly coiled seminiferous tubules, within which sperm production occurs.
In contrast to female eggs, sperm are continually produced throughout a man's lifetime. During spermatogenesis and transport through the male reproductive tract, the male spermatozoa are transformed into a highly specialized cell with its own motility and enzymatic capacity to penetrate the egg. Epididymal function must be normal and the accessory glands must be functional to produce normal seminal plasma. An intact nervous system is also required to permit penile erection and normal ejaculation.
Male infertility can be divided into:
Problems with sperm production is by far the most common of the three, and can be detected during semen analysis. There are many causes of abnormal sperm production, including:
An initial male fertility examination includes a medical history, physical examination, general hormone tests and one or more semen analyses, which measure semen volume as well as sperm number, ability to move spontaneously and quality of motion.
Initial questions may include:
Next, you will receive a thorough physical examination to evaluate the pelvic organs — the penis, testes, prostate and scrotum.
Any fertility treatment may be expected to have an effect on semen quality roughly three months after it is started, as this is the length of time required for a single cycle of spermatogenesis, or sperm production. If neither surgical nor medical therapy is appropriate, assisted reproductive technologies are possible.
In choosing a treatment plan, consideration should be given to each couple's long-term goals, financial constraints, and the results of the female partner's evaluation in addition to male factor findings.
The most successful medical therapy for male infertility involves reversing chemical, infectious or endocrine imbalances. This is called specific therapy, and it is usually successful because treatment is based on the correction of well-defined problems.
Examples of this include:
Reviewed by health care specialists at UCSF Medical Center.