Females are choosy…even at the molecular level

1bef6bc833So: this is interesting. Human eggs appear to be choosy about the sperm they attract to themselves.

Human eggs release compounds called chemoattractants into this fluid, which chemically communicates with sperm. While the exact chemicals are yet to be identified (some researchers suspect progesterone is involved), whatever it is can trigger sperm to change swimming directions.

“Follicular fluid from different females consistently and differentially attracts sperm from specific males,” the team wrote in their paper, finding that eggs attracted between 18 to 40 percent more sperm from their preferred males.

(Not, note, specifically the egg owner’s preferred male, but a preferred male.)

Scientists have also found that mouse IVF eggs prefer sperm from less related males. But this is the first example of human egg preferences, so the reasons and mechanisms behind it are still up for discovery.

Mind, there’s the very large caveat that the study’s methods might have–AKA, almost certainly will have–influenced the results.

For example, the IVF eggs they used had been through treatments that may have changed some biological processes.

Also, the concentrations of sperm were much higher than natural (20,000 sperm per egg instead of the average of around 250) and they were placed quite close to the egg – which may minimise differences in the effects of chemoattractants.


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