When Sperm Meets Egg, Sparks Fly

The attraction is visible. And it serves as a guiding light to better IVF.
ByAnisa Arsenault
Associate Editor
May 2016
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For the first time, researchers have been able to capture imagery of the instant when sperm makes contact with a human egg. The burst of light emitted isn’t just picture-perfect; it could also help measure the viability of the future embryo.

A team of Northwestern University researchers first noticed the emission of zinc atoms at the moment of fertilization in 2011, but that was only in mice. Now, using sperm enzymes (not actual sperm, since federal law prohibits that in human research), they were able to come to a stunning conclusion for humans: the stronger the spark, the better quality of the egg.

Senior study author Teresa Woodruff says this has big implications for infertility treatments.

“This means if you can look at the zinc spark at the time of fertilization, you will know immediately which eggs are the good ones to transfer in in vitro fertilization,” she says. Zinc is responsible for the development and growth of an egg into a new genetic organism. “It’s a way of sorting egg quality in a way we’ve never been able to assess before.”

Co-author Eve Feinberg, MD, explains that better egg selection will lead to a much earlier determination of whether or not an embryo is viable.

“There are no tools currently available that tell us if it’s a good quality egg,” she says. “Often we don’t know whether the egg or embryo is truly viable until we see if a pregnancy ensues. That’s the reason this is so transformative. If we have the ability up front to see what is a good egg and what’s not, it will help us know which embryo to transfer, avoid[ing] a lot of heartache and achiev[ing] pregnancy much more quickly.”

These findings were published on April 26 in Scientific Reports. Watch this video explain more about the process.

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