#Women’s bodies can weed out ‘unwanted’ sperm, study finds

“#Women’s bodies can weed out ‘unwanted’ sperm, study finds”

August 19, 2020 | 12:34pm

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Undesirable sperm may not stand a chance thanks to a newly discovered function in the female reproductive tract.
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Men can get rejected even after sealing the deal.

Contrary to popular belief, the fastest sperm don’t always finish first. Various chemicals in the female reproductive system can also determine which sperm are successful, according to a new study published Wednesday in the journal Proceedings of the Royal Society B.

“The whole reproductive tract of the female seems to have evolved to filter out ‘unwanted’ spermatozoa,” Jukka Kekäläinen, a biology professor at the University of Eastern Finland who co-authored the study, told CNN.

Specifically, the cervix acts as a reproductive bouncer of sorts — both rejecting “abnormal” sperm, while aiding swimmers that give the woman’s offspring the best chance of survival, per the research. A prior study by the same team found that a woman’s follicular fluid serves the same purpose, CNN reports.

To test the organ’s selective function, the team combined all possible variations of cervical fluid of nine women with the sperm of eight men, and then compared swimmers’ finishing rate to the genotype of each participant.

Interestingly, they found that the most compatible sperm were also the least genetically similar to the egg. The phenomenon can be chalked up to the fact that “the more diverse those genes are, the more diverse are the kinds of infections you can fight,” said John Fitzpatrick, an associate professor in the department of zoology at Stockholm University in Sweden.

He added, “If your partner has a slightly different combination of these genes than you do, then you’re going to produce offspring that can fight an even broader array of pathogens and diseases.” So yes, diversity is a sperm’s greatest strength.

Most importantly, the game-changing research could help doctors more accurately diagnose why certain couples can’t conceive.

“We would encourage future infertility research to test the possibility that infertility is not always a pathological condition, but instead can also result in demonstrated evolutionary mechanism,” said Kekäläinen.

Reproductive fluids aren’t the only chemical indicators of whether a mate is viable. Studies show that the scent of one’s sweat plays a crucial role when it comes to picking sex partners.