It may seem like sparks (the literal and figurative kind) only happen in the movies. But as it turns out, sparks are a real human phenomenon that science has only documented recently. And the flash of light marks one of the most momentous events in human biology: when a sperm meets an egg to conceive a baby!
Scientists at Northwestern University captured, for the first time, the ‘fireworks' display when a sperm fertilizes a human egg. The phenomenon is dubbed a "Zinc spark," and results from the surge of zinc that gets released from the egg once a sperm enters. Using fluorescent markers, the scientists were able to show exactly what happens at the moment of conception.
That fertilization can be visualized so clearly can be an extremely powerful tool in assisted reproductive technology. For example, people who undergo in vitro fertilization may have a higher chance of success if doctors are able to first screen, using the zinc spark test, and select only eggs that have been successfully fertilized for implantation. Overall, the zinc signal provides a non-invasive and reliable way to assess the health of the egg and the subsequent embryo.