A discovery by researchers in the United States has shed important new light on male infertility, and could provide the basis for a cure.
Mr. Osamu Tsutsumi and his colleagues at the National Institute of Health in Bethesda, Maryland, have found that a chemical called epidermal growth factor (EGF) plays what appears to be a key role in helping mice sperm mature.
Because EGF is also produced by humans, the researchers reason that it could play a similar role in man, and that under-production of the chemical could lead to low sperm counts and infertility.
How Does EGF Impact Sperm Production?
EGF is produced in the mouse’s sub-mandibular gland and until now its biological role has been unclear.
When the scientists removed the gland from mice, so cutting off the supply of EGF, they found that the levels of mature sperm dropped by as much as 55 percent.
But when EGF was administered to the glandless mice, their sperm counts recovered completely, suggesting a link between EGF levels and sperm production.
Narrowing Down The Role Of EGF
Mr. Tsutsumi and colleagues investigated the role of EGF more deeply by examining how sperm at different stages of maturity were affected by EGF deficiency.
Sperm are formed in three distinct stages, and the researchers found that EGF deficiency appeared to disrupt the second stage of production.
They noted that levels of sperm in the first growth phase were abnormally high in mice lacking the sub-mandibular gland. That, they conclude, is because EGF, the trigger which appears to start the second phase of growth, is absent.
Nevertheless, the researchers have no idea, as yet, how EGF activates the second stage of production. They know, however, that EGF is not the only trigger for sperm growth, otherwise mice without the capacity to generate it would have had a zero sperm count.
The theory that some cases of infertility may be attributable to EGF deficiency gains ground, they add, given that seminal fluid samples taken from some human subjects show marked immuno-reaction against EGF.