Fireworks mark moment that human life begins
Sparks fly at the point of conception – and the size of the flash may determine the quality of the embryo
HUMAN life starts in a bright flash of light as a sperm meets an egg, scientists have shown for the first time after capturing the astonishing “fireworks” on film. An explosion of tiny sparks erupts from the egg at the exact moment of conception.
Scientists had seen the phenomenon occur in other animals but it is the first time it has been shown in humans.
Not only is it an incredible spectacle, highlighting the moment a new life begins, but the size of the flash may determine the quality of the fertilised egg.
Researchers from Northwestern University, in Chicago, noticed that some of the eggs burned brighter than others, showing that they are more likely to produce a healthy baby.
The discovery could help doctors pick the best fertilised eggs to transfer during in vitro fertilisation (IVF).
“It was remarkable,” said Prof Teresa Woodruff, one of the study’s two authors and an expert in ovarian biology. “We discovered the zinc spark just five years ago in the mouse, and to see the zinc radiate out in a burst from each human egg was breathtaking.
“This means if you can look at the zinc spark at the time of fertilisation, you will know immediately which eggs are the good ones to transfer in in vitro fertilisation. It’s a way of sorting egg quality in a way we’ve never been able to assess before.”
Currently around 50 per cent of fertilised eggs do not develop properly and experts believe that faulty genetic code could be responsible.
Some clinics take videos of the egg developing to try to pick up problems, while others check for genetic mutations, but that is an invasive procedure that can damage the tiny egg. Often a decision is just down to a clinician deciding which eggs look the healthiest.
But the new findings could give an extra indication that an egg is flourishing. A video of nine human eggs coming into contact with sperm enzyme showed two flashed much brighter than the rest.
“This is an important discovery because it may give us a non-invasive and easily visible way to assess the health of an egg and eventually an embryo before implantation,” said co-author Dr Eve Feinberg.
“There are no tools currently available that tell us if it’s a good-quality egg. 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.”
The bright flash occurs because when sperm enters an egg it triggers an increase in calcium which releases zinc from the egg.
As the zinc shoots out, it binds to small molecules which emit a fluorescence which can be picked up by camera microscopes.
Over the past six years the team has shown that zinc controls the decision to grow and change into a new genetic organism.
“These fluorescence microscopy studies establish that the zinc spark occurs in human egg biology,” said Prof Tom O’Halloran, a co-senior author.
The study