It’s a race to the finish and he’s got millions of others to beat. The finish line isn’t even a line at all; it’s a translucent yellow sphere. This is the race of life, or rather fertilisation.
In humans, fertilisation is when a man’s sperm journeys through a woman’s reproductive organs to reach her egg. The basic process is largely the same across most mammals, so let’s take a closer look at humans.
This race isn’t kicked off by a firing gun, but is no less dramatic as sperm shoot into a woman’s vagina at an average speed of 30 mph. Swimming through the woman’s womb as fast they can, the first sperm to reach the egg is the winner.
When a sperm finally meets an egg, things get really intimate. The sperm releases a cocktail of substances that break through the outer coating of the egg, paving the way for the sperm to burrow its way in. The sperm is after all 30 times smaller than the egg, so it needs all the tools at its disposal to get in.
Once the sperm has made some headway getting past the eggs outer coating, two become one. That is to say the sperm and the egg fuse together and the DNA safely stored inside each of them mixes together. This new mix of DNA, made in part from a man’s sperm and a woman’s egg, is what provides the instructions for a whole new individual to grow and develop.
The mash-up between the sperm, the egg, and the new combination of DNA forms a cell called a zygote. Mission accomplished – fertilisation complete.
Of course now the zygote has to make a home for itself nestled in the woman’s womb and begin the complicated journey of becoming a baby.