On your mark. Get set. Go!
In the race for conception, most of us have been taught it’s the strength and swiftness of the wiggling ejaculate that determines which sperm gets to the finish line first.
But science is beginning to learn that various chemicals in the female reproductive system can facilitate — or sabotage — that sperm’s chance for victory.
And it appears to happen at an early stage in the race — in a woman’s cervix. A sperm’s swimming motion, speed and viability are affected by the level of genetic compatibility between a female’s cervical mucus and the male’s sperm, found a new study that published Wednesday in the Proceedings of the Royal Society B journal.
A prior study by the same authors found the same thing occurred in a woman’s follicular fluid.
Think of it as a chemical “sorting hat” — dictated by a female’s reproductive secretions — that help sperm who are most likely to give her offspring a genetic boost in survival.
“The whole reproductive tract of the female seems to have evolved to filter out ‘unwanted’ spermatozoa,” said Jukka Kekäläinen, an associate professor in the department of environmental and biological sciences at the University of Eastern Finland who authored both studies.
“We argue that cryptic female choice can potentially occur in multiple stages during the sperm migration from the vagina towards the unfertilized egg,” she said.
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