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How does male reproductive system work
The two essential contributors to male fertility are sperm production and sperm transport.
An adult man produces millions of sperms everyday after puberty. The process of sperm production or spermatogenesis is a long and continuous process, taking up to 3 months. It begins in the seminiferous tubules of the testis, where sperm cells undergo repeated cell division to finally produce a mature sperm. The sperms are then stored in the epididymis and it is here that the sperms finally mature and gain the ability to swim. The next passage of the sperms is in the vas deferens which is a tube connecting the epiphysis to the urethra via the ejaculatory duct. It is from the urethra that the sperms are ejaculated during coitus. The seminal fluid is formed with not only the sperms but also receives a lot of secretions from other gland like seminal glands, prostrate and Cowpers gland. The secretion plays a vital role in the ability of the sperm to move and fertilize the egg. In addition to healthy structures mentioned above, adequate levels of male hormone- testosterone and ambient temperature of the scrotum are also essential for sperm production and maturation. Testes play a vital role in production of testosterone. Therefore, testicular dysfunction can lead to disturbances in testosterone production also.
Evaluation of male partner
There can be multiple reasons for male factor infertility ranging from hormonal imbalances, to physical problems, to psychological and/or behavioural problems. The important and correctable causes are listed below for easy understanding.
The evaluation of the male begins with detailed history and physical examination of the male partner and semen analysis.
It is a laboratory assessment of the quality and quantity of sperms present in the semen. It is one of the initial tests done to assess if the male has any fertility issues. The semen analysis is done according to certain set guidelines to determine if it is normal. Generally the male collects a semen sample in a sterile container by masturbation after an abstinence of 3-5 days. The sample is than left to liquefy for about 30 min as semen is a viscous liquid. Later a slide is made of the liquefied semen and then the count, motility and morphology of the sperms is assessed under microscope. At least 2 semen analyses performed at least 6 weeks apart are essential for proper evaluation and arriving at a diagnosis.
Normal semen parameters
a) Sperm concentration – often referred to as a sperm count, it is the number of sperm present in each milliliter of fluid. A normal concentration is 15 million per milliliter.
b) Sperm motility – This is the percentage of sperms which are mobile. At least 40% of the sperms in an ejaculate should be motile and 32 % sperms should be progressively motile.
c) Semen volume – This refers to the total amount of fluid collected in the sperm sample. Semen volume between 1.5- 5 milliliters per ejaculate is considered normal.
d) Total motile sperm count – This is the count of total number of moving sperm in the sample. Normally, there are at least 15 million motile sperm in the sample.
e) Sperm morphology – This refers to the shape of the sperm. Surprisingly, abnormally shaped sperm are common. As per the latest World Health Organization (WHO) criteria for assessing morphology of sperms, the sample is considered normal if more than 4% sperms are normal.
f) Viscosity – Viscosity refers to thickness of the sperm fluid. Low or moderate viscosity is considered normal.
g) Leukocytes – Leucocytes are the white blood cells, presence of which in semen is a sign of inflammation or infection. A small number of leukocytes can be present in normal semen also. But, presence of more than one million leukocytes per milliliter of semen is considered abnormal.
Advanced techniques of sperm assessment
a) Vitality Testing– vitality testing is of importance when all the sperms are immotile. This test helps in differentiating dead immotile sperms from viable immotile sperms. The viable immotile sperms can be picked and used for fertilizing the eggs with ICSI.
b) Sperm DNA fragmentation– Sperm DNA fragmentation refers to the breakage in the DNA of the sperm and indicates the damage to the genetic material of the sperm. The DNA damage can occur at any time from the stage of sperm manufacture when the immature sperms may be exposed to hostile conditions or during the storage time in the epididymis by the reactive oxidative species which react with the DNA of the sperms and produce breakage and fragmentation in the DNA. The presence of Increased DNA fragmentation has been found to correlate with ICSI failures, recurrent miscarriage and poor pregnancy outcomes. Some tests have now been developed which detect the percentage of sperms in the semen sample have DNA fragmentation which is expressed as DNA fragmentation Index(DFI), though there is still some controversy about what level of DN fragmentation should be regarded as the threshold for threat to DNA integrity.
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