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Sperm make an impressive journey through a woman's body, and one succeeds in fertilizing the egg.
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The race starts with the act of love. Tens of millions of spermatozoa rush ahead on a hunting trip that may eventually lead to a fateful encounter and a promise of new life.
Only one can win. The rest will end their lives in a matter of days. In the marathon race to life there are no consolation prizes. Only one winner will merge with the ovum.
The sperm move forward by wiggling their tails through the dangerous obstacle track, the acidity in the vagina, the cervix, and the uterus.
The obstacles claim many lives. The slow and weak give up. Others go off track, lose direction, or get trapped. The road separates into two fallopian tubes, but there is an ovum waiting in only one of them.
Not only stamina and talent count, this journey also requires a lot of luck.
Strong currents prevent the sperm from continuing forward. The follicles on the uterine wall capture many and hold them back.
Finally, at the end of the tunnel, like a mysterious star – the ovum. The sperm attack is merciless. A sperm cell carries a mysterious load: each can create a unique human being unlike any other in the world.
Now there are only about 100 sperm left competing for the ovum, but only one will make it through the ovum's protective layer. In their final efforts, one suddenly manages to penetrate. It is the winner.
After the ovum is pierced, it hardens and becomes impermeable. For the rest of the sperm, the journey has ended in failure. For the winner, it is the beginning. It sheds its now unnecessary tail and load, and is free.
The father's genetic material merges with the mother's. A new and unique cell is created: the fertilized ovum. At this moment, almost all of
the future baby's features are determined and fetal development begins.