Human eggs prefer some men鈥檚 sperm over others, research shows
Human eggs use chemical signals to attract sperm. New research from Stockholm University, 91直播 University NHS Foundation Trust and The University of Manchester shows that eggs use these chemical signals to 鈥渃hoose鈥� sperm. Different women鈥檚 eggs attract different men鈥檚 sperm 鈥� and not necessarily their partners.
Humans spend a lot of time and energy choosing their partner. A new study by researchers from Stockholm University and 91直播 University NHS Foundation Trust (MFT) shows that choosing your partner continues even after sex 鈥� human eggs can 鈥渃hoose鈥� sperm.
鈥淗uman eggs release chemicals called chemoattractants that attract sperm to unfertilised eggs. We wanted to know if eggs use these chemical signals to pick which sperm they attract,鈥� said John Fitzpatrick, an Associate Professor at Stockholm University.
The researchers examined how sperm respond to follicular fluid, which surrounds eggs and contains sperm chemoattractants. The researchers wanted to find out if follicular fluids from different females attracted sperm from some males more than others.
Microscopic mate choice
鈥淔ollicular fluid from one female was better at attracting sperm from one male, while follicular fluid from another female was better at attracting sperm from a different male,鈥� said Professor Fitzpatrick.
鈥淭his shows that interactions between human eggs and sperm depend on the specific identity of the women and men involved.鈥�
The idea that eggs are choosing sperm is really novel in human fertility
The egg does not always agree with the women鈥檚 choice of partner. The researchers found that eggs did not always attract more sperm from their partner compared to sperm from another male.
Is this egg or sperm choice? Professor Fitzpatrick explained that sperm have only one job 鈥� to fertilise eggs 鈥� so it doesn鈥檛 make sense for them to be choosy. Eggs on the other hand can benefit by picking high quality or genetically compatible sperm.
鈥淭he idea that eggs are choosing sperm is really novel in human fertility,鈥� said , the Scientific Director of the Department of Reproductive Medicine at Saint Marys鈥� Hospital, which is part of MFT, and the senior author of this study.
The University of Manchester Honorary Professor added: 鈥淩esearch on the way eggs and sperm interact will advance fertility treatments and may eventually help us understand some of the currently 鈥榰nexplained鈥� causes of infertility in couples.
鈥淚鈥檇 like to thank every person who took part in this study and contributed to these findings, which may benefit couples struggling with infertility in future.鈥�
The article Chemical signals from eggs facilitate cryptic female choice in humans is published in the scientific journal Proceedings of the Royal Society B.