This photo shows a winner!
Of the approximately 200 million at the starting gate, he was the strongest and the luckiest to reach the intended destination: the egg cell.
At the moment he crosses the finish line—this is hard to believe—the photographer captured the exact moment of penetration:
After the sperm has penetrated, the egg closes its 'doors' to all latecomers.
The photos above and the following were taken by Swedish photographer Lennart Nilsson, who observed and documented the incredible developmental process of human embryos from fertilization to birth. To do so, he adapted a cystoscope—a device commonly used for bladder examination—with a lamp and a special camera.
On the 18th day after fertilization, the heart of the embryo begins to beat.
(Aristotle already knew that the heart developed first; he used 21 chicken eggs and opened one every day. Because he saw the heart first, he argued that it must be the seat of the psyche—he had other arguments as well).
The embryo after 22 days. The gray area will later form the brain.
After 10 weeks:
Another month to go and then another race begins, one that lasts a lifetime: