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Friday, July 3, 2015

Male subfertility

In the human, the process of spermatogenesis starts at puberty and continues throughout life. The total process of spermatogenesis in humans takes 74 days within the seminiferous tubules. It takes a further ten days for the sperm to travel to the epididymis to be stored for use during ejaculation. The head of the epididymis stores 70 per cent of the mature sperm and, during ejaculation, the sperm exit via the vas deferens which then passes through the inguinal canal and opens into the urethra adjacent to the prostate.

The supporting cells of the testis are the Leydig and Sertoli cells. The Leydig cells are contained in the connective tissue of the testis and are the prime source of the male hormone, testosterone. LH from the pituitary gland regulates Leydig cell function by the negative feedback loop. The Sertoli cells are highly specialized cells that maintain the integrity of the seminiferous epithelium (so that spermatogenesis can occur in an immune privileged area) as well as nourish the developing sperm.
Approximately one in 20 men are subfertile, about 85 per cent have suboptimal semen quality, while azoospermia, coital dysfunction and immune factors contribute to the rest.

Any factors, whether genetic, physiological, pathological or mechanical, that affect the spermatogenesis process from the production to time of ejaculation will influence male fertility.

Causes for male sub fertility
Sperm production problems
• Chromosomal or genetic causes
• Undescended testes (failure of
the testes to descend at birth)
• Infections
• Torsion (twisting of the testis in scrotum)
• Varicocele (varicose veins of the testes)
• Medicines and chemicals
• Radiation damage
• Unknown cause
Blockage of sperm transport
• Infections
• Prostate-related problems
• Absence of vas deferens
• Vasectomy
Sexual problems
(erection and ejaculation problems)
• Retrograde and premature ejaculation
• Failure of ejaculation
Erectile dysfunction
• Infrequent intercourse
• Spinal cord injury
• Prostate surgery
• Damage to nerves
• Some medicines
Hormonal problems
• Pituitary tumours
• Congenital lack of LH/FSH (pituitary problem from birth)
• Anabolic (androgenic) steroid abuse
Sperm antibodies
• Vasectomy
• Injury or infection in the epididymis
• Unknown cause

Diagnosis
Semen analysis should be performed after the patientshave abstained from sexual intercourse for 3–4 days.

Two abnormal test results are required to diagnose male subfertility. For men with a very low sperm count or azoospermia, it is important to check their testosterone level (low levels suggest a production impairment) and LH/FSH. (Hypogonadotrophic hypogonadism is rare and can be treated with FSH and hCG injections.)

It is also important to screen for the cystic fibrosis (CF) mutation as a congenital bilateral absence of the vas deferens (CBAVD) is a minor variant of cystic fibrosis. If the male partner is found to have the CF mutation, it is important to screen the female partner for it. If both partners are carriers, there is a one in four chance of the child being affected by CF and therefore the couple will require pre-conceptual genetic counselling prior to assisted conception. Karyotyping is also offered as there may be Y chromosome deletion defects (AZF region). Specific types of Y chromosome deletion, namely AZFa and AZFb Y chromosome deletions, carry poor prognosis for surgical sperm retrieval procedures.

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