Male reproduction: anatomy, function & conception problems
The anatomy of fertility
- Penis: During sexual stimulation, the penis becomes erect as its spongy tissue fills with blood. The penis delivers seminal fluid containing sperm into the vagina on ejaculation.
- Testes: The testicles or gonads are located in a pouch of skin behind the penis called the scrotum. They produce sperm and release the male sex hormone testosterone. About two months before birth, the testes descend through the abdominal wall into the scrotum.
- Scrotum: The pouch of skin below the penis, which hold the testes. To produce and nurture sperm, the temperature within the testes remains around 1°C cooler than normal body temperature.
- Epididymis: A tightly coiled tube located on the top of the testes. Sperm are stored in the epididymis for up to two weeks, where they mature and develop mobility for fertilization.
- Vas deferens: A long curving tube that forms part of the sperm transport system. It also provides storage for most of the sperm until ejaculation.
- Seminal vesicles: Two pouches located behind the bladder, which produce part of the seminal fluid, which transports and nourishes sperm.
- Prostate gland: A chestnut-sized gland below the bladder, which produces 60% of the seminal fluid used to transport sperm. The fluid helps neutralise acid levels in the male urethra and his partner’s vagina, which in high concentration, can kill sperm.
| If you and your partner are not conceiving, your doctor will typically begin with the simplest and least invasive tests. If the cause of conception difficulties is not identified, more involved tests may be scheduled. Find out about preliminary fertility investigations. |
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A reminder of the basics
Millions of sperms develop daily in the testicles within a system of tiny tubes known as the seminiferous tubules. As sperm are produced, they pass from the testes to the epididymis, an organ that stores and nourishes sperm as they mature. The entire hormone-regulated process of sperm maturation, from their primitive beginnings in the seminiferous tubules to their fully mature form in the vas deferens, takes about 74 days. During intercourse a man releases semen, a combination of sperm from the epididymis and a fluid from the seminal vesicle and prostate glands. Sperm can live for 48 to 72 hours within the female reproductive tract, while retaining the ability to fertilize an egg.
| Hormones play an important role in regulating reproductive processes. Deepen your understanding of conception and the complex role hormones play. |
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Identifying the cause of the problem
Conception difficulties are common. Almost one in ten couples has difficulties conceiving1, but infertility is just as likely to be due to your partner’s health as your own. In fact 15-25% of cases involve both partners and 20% remain unexplained.2 It is important that both partners are thoroughly investigated to determine the right course of action.
In men, the most common fertility issue is the production of sufficient normal, motile sperm. Here are some common problems men face:
Varicocele
Varicocele is the presence of varicose veins around the testicles. It occurs when blood does not circulate out of the testicles properly. The increase in blood leads to a rise in the temperature in the testicles. This causes abnormal testosterone levels, which hinder the production of sperm.
Undescended testicles
As a baby boy develops in the uterus, his testicles typically form inside his abdomen and descend into the scrotum shortly before birth. When the move doesn’t take place, the baby is born with a condition known as cryptorchidism. Usually the testicles descend themselves by the sixth month of life. Untreated, undescended testicles may affect fertility or lead to other medical problems.
| Oligospermia is where too few sperm are produced. Azoospermia is a complete absence of sperm. |
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Testicular cancer
Testicular cancer is sometimes diagnosed when a couple is experiencing difficulties conceiving. A malignant tumour that develops in the testicle may destroy testicular tissue. If not detected early enough it may also spread to other parts of the body.
Diabetes
Diabetes has been found to have an effect on the quality of sperm.
Surgery or injury
Serious trauma to the testicles can affect the production of sperm and possibly lead to sterility. Damage from sport or by accident can rupture vessels that supply blood to the testicles. Additionally, surgery to correct an undescended testicle or repair a hernia may lead to damage of a man’s sperm-producing capabilities.
Physical abnormalities
In a small number of men, the fluid deposited in the vagina during intercourse may not contain sperm. This may be due to a blockage or malformation of the epididymis, which prevents the sperm from combining with other fluids to create semen.
Overheating
Heat can have a detrimental effect on normal sperm production. Too much time spent soaking in a hot tub can raise the temperature of the testicles and interrupt sperm production.
Too much stress, fatigue or alcohol
Overwork, anxiety and too many alcoholic drinks have a negative affect on libido. Until recently, most cases of impotence were thought to be psychological. However, new oral treatments offer widespread success.
| Female fertility declines with age, as do treatment success rates.3 If you and your partner are not successful with the initial treatment, discuss with your doctor when is the right time to seek help in a specialized fertility clinic and consider advanced treatment options. |
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1. Boivin J et al, International estimates of infertility prevalence and treatment seeking: potential need and demand for infertility medical care. Hum Reprod. 2007;22: 1506-1512. 2. Collins J.A. Evidence-based infertility: evaluation of the female partner. International Congress Series 2004;1266: 57–62. 3. Age and Fertility. A Guide for Patients. ASRM 2003; http://www.asrm.org/Patients/patientbooklets/agefertility.pdf
