Conception, the act of becoming pregnant, has all the ingredients of a most exciting drama, carried out on a microscopic scale.
In coitus (sexual intercourse), a healthy man releases about a tea-spoonful of semen into the vagina of his mate. This semen contains from 300 to 400 million spermatozoa, or male germ-cells, also called sperm. Any one of these can fertilize the egg-cell of the woman.
The spermatozoa face their first hazard in the vagina, whose acid secretions kill millions of them. However, many escape, swimming up through the vagina by means of their whip-like tails. Those with sufficient energy proceed through the cervical canal into the womb, or uterus, and on into the Fallopian tubes. In one of these two tubes, an egg-cell may be waiting if the female has ovulated.
This takes place at about the midpoint of the menstrual cycle. If all goes well, the chances are that a male cell will reach the female cell and penetrate it. In that moment, a new life is created.
Once the head of the sperm has penetrated the egg, the tail disappears. The vital material that is the father’s contribution to the heredity of the offspring is in the forepart of the sperm. The moment a particular sperm has penetrated and fertilized a particular egg, all the characteristics that a child can inherit are determined. Whether your baby will be blonde or brunette, whether his eyes will be blue or brown, is settled. Whether your baby will be a boy or a girl depends on the sperm; an egg-cell can develop into either a boy or a girl.
Whether or not you will have twins or triplets is also decided very soon after this important moment.
Soon after this magical moment of fertilization, the egg-cell begins to divide. More cells appear. About five days to a week later, the tiny embryo travels to the wall of the uterus. There it digs out a little hole for itself, and a cover forms over it, so that it is attached to the wall of the uterus in a protected, completely enclosed pocket. It begins to grow rapidly. By about the twenty-eighth day after fertilization, the embryo is large enough to be seen without the aid of a microscope.
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