Eggs select best sperm: study
YOU may think he’s the one – but what do your eggs think? A new study has found that a woman’s eggs are especially selective when choosing the most ideal sperm for fertilisation.
Looking at leftover samples from 16 couples having reproductive treatment, researchers from Sweden found eggs release a chemical that attracts only certain types of sperm, regardless of whether they come from the woman’s chosen partner, say findings published last week in the journal Proceedings of the Royal Society.
The selectiveness could be a way of sorting out the mate with the best genes, said study author John Fitzpatrick, an assistant professor in the department of zoology at Stockholm University in Sweden.
“We expected to see some sort of partner effect, but in half of the cases the eggs were attracting more sperm from a random male,” he told CNN. “The most likely explanation for this is that these chemical signals allow females to choose males who are more genetically compatible.”
The researchers knew that eggs release chemicals during ovulation known as chemoat-tractants, which Fitzpatrick says act like a “breadcrumb trail” for sperm to track down the egg. In this study, they found that as little as 18 per cent of sperm can even find the trail. When they do pick up on the signal, the sperm swim more vigorously toward the egg, increasing the chances of fertilisation.
Fitzpatrick and his colleagues believe by attracting sperm with more diverse genes than the egg has, it could ultimately arm the baby with a better immune system.