| The
male genital tract includes the testes, the epididymis, the vas, the
prostate and urethra. The testes situated in the scrotum are mainly
made up of loops of fine tubes (seminiferous tubules) which produce
the sperm. The sperm cells mature as they pass through the epidiymis
(a narrow system of tubes on the surface of the testes). The vas is
a hollow tube, which carries the sperm from the epididymis to the urethra.
It takes
3 - 4 months for sperm to develop, during this time sperm production
may be affected by febrile illness, exposure to drugs, toxins, radiation,
local trauma or infection.
The primary
laboratory test for male fertility is " semen analysis". The
sample is obtained by masturbation or collected from a special condom
following intercourse. Sterile containers must be used to collect the
sample following three days of sexual abstinence.
A
normal assessment should show :
- Semen volume - 2-4mls
- Sperm count - more than
20 million per ml
- Sperm motility - more
than 50% moving
- Sperm morphology - more
than 30% of normal shape
- White blood cells -
should be less than 1 million per ml
- Antisperm antibodies
test - should be negative
Common Male Infertility Problems :
-
Abnormal Sperm parameters :
Low sperm count - (oligospermia)
Poor sperm motility - (asthenospermia)
High abnormal forms - ( teratospermia)
-
Immunological
factors : - Antisperm antibodies may occur following surgery,
trauma or infections of the genital tract. Antisperm antibodies
impair sperm motility and their ability to penetrate and fertilise
an egg.
-
Absence
of Sperm : - (azoospermia) May be due to an obstruction
at the level of the vas, epididymis, or even the testes, caused
by previous infections, trauma or surgery. It may also be due to
a bilateral congenital absence of the vas. Azoospermia could also
be due to testicular failure caused by hormonal, chromosomal abnormalities,
previous infection such as mumps or undescended testes.
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A
single sperm consists of a head, which contains the man's genetic
information and its tip, an acrosome which will help the sperm
penetrate the outer shell of the egg; a midpiece, which supplies
the energy needed for movement; and the tail which propels the sperm
forward. |
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