Light is sometimes used as a metaphor for life — you might "put someone's lights out" or tell them they're "the light of your life." But life and light aren't just linked poetically. When sperm meets an egg, there is a real flash of light.
Researchers at Northwestern University made this startling discovery in 2011, when they saw what they call "zinc sparks" at the point of conception in mice. In 2014, they figured out a way to capture images of the event taking place. And in 2017, they achieved the holy grail of biological research: the team observed the same thing occurring in human egg cells.
Egg cells rely on zinc for their most vital functions, from maturing into a healthy egg to developing into an embryo. The 2014 research showed that each human egg cell comprises around 8,000 zinc compartments, each of which contain a million zinc atoms.
When sperm meets an egg — although, as the human experiments demonstrated, all you really need is a sperm enzyme — the egg releases a flurry of zinc atoms all at once. Under the researcher's fluorescent sensor, it looks like a microscopic fireworks show, studded with explosion after tiny explosion. The spectacle lasts for up to two hours after conception.# header