New research shows that eggs prefer some men’s sperm over others

New research shows that eggs prefer some men’s sperm over others

Humans spend a lot of time and energy choosing their partner. A new study by researchers from Stockholm University and Manchester University NHS Found

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Humans spend a lot of time and energy choosing their partner. A new study by researchers from Stockholm University and Manchester University NHS Foundation Trust (MFT) shows that choosing your partner continues even after sex.

Human eggs use chemical signals to attract sperm and this new research shows that eggs use these chemical signals to choose sperm. Apparently, different women’s eggs attract different men’s sperm—and not necessarily their partner’s.

“Human eggs release chemicals called chemoattractants that attract sperm to unfertilized eggs. We wanted to know if eggs use these chemical signals to pick which sperm they attract,” 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.

“Follicular 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. This shows that interactions between human eggs and sperm depend on the specific identity of the women and men involved,” said Professor Fitzpatrick.

The egg does not always agree with the women’s 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—to fertilize eggs—so it doesn’t make sense for them to be choosy. Eggs on the other hand can benefit by picking high quality or genetically compatible sperm.

“The idea that eggs are choosing sperm is really novel in human fertility,” said Professor Daniel Brison, the scientific director of the Department of Reproductive Medicine at Saint Marys’ Hospital, which is part of MFT, and the senior author of this study.