Video: New Technique Shows 'Sparks' Fly At Moment of Conception

Eggs emit zinc when they are activated, just before the process of fertilization, in "sparks" that can be visualized using a new technique. Northwestern University

At the moment of conception, eggs of several mammals send out a pulse of metallic ions as they undergo cellular change. Researchers have come up with a new method to visualize this event, which appears like a spark of color being emitted from the cell. For the first time, scientists have now observed this "spark"—caused by the release of charged particles of zinc, a metal that plays a pivotal role in the metabolism and development of the egg and embryo—emitted from human eggs.

The findings were published April 26 in the journal Scientific Reports. Previous work on mouse embryos shows that eggs of higher quality produced stronger zinc "sparks," and it's likely that the same would hold true in humans, according to Teresa Woodruff, an expert in ovarian biology at Northwestern University. In a statement, she said the discovery could lead to a way of sorting egg quality to improve in vitro fertilization (IVF) techniques.

"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 IVF," Woodruff said.

The researchers used molecular probes that produce fluorescent light upon binding to zinc, creating the "sparks" visible in the video.

The human egg produced this exodus of zinc at the moment of activation, a cellular process that immediately precedes fertilization. The researchers used a protein from sperm cells to activate the eggs but didn't actually fertilize them, as that's currently illegal under federal law.