So why do sparks literally fly at the moment of conception?
Back in 2011, the Northwestern team discovered that sparks of zinc exploded at the point of conception in mice.
It took them a few years to figure out how to image this event,
but by 2014, they’d managed to film the event for the first time ever, and watched as billions of zinc atoms were released at the exact moment when a mammal's egg is pierced by a sperm cell.
Using a new fluorescent sensor that's able to track the movements of zinc in live cells, the team caught a glimpse of an egg’s zinc-storage capabilities, and found some 8,000 zinc compartments, each one containing around 1 million zinc atoms, just ripe for exploding. The tiny 'fireworks' that result were found to last for about 2 hours after fertilisation.
Now, the same team has managed to film this event occurring in a human egg at the point of conception.