What really happens during conception?

The reproductive process seems simple enough. See sperm swim. See sperm fertilize egg. See Missy ask for a pony for her fifth birthday. But conception is far from simple. Here's how it happens, in a nutshell:

Every woman is born with the number of eggs she'll have in her lifetime. Those eggs live in her two ovaries. Every month-during ovulation-the ovaries usually release one egg cell (not one each but one between the two ovaries-it is really a complex process) from its follicle and send it on a very dangerous journey inside the body.

On the other side of the sheets, sperm begins the race when it hears the starter's pistol (ejaculation). Before that point, sperm must line up in a half mile worth of tubes before they get to the penis (which guys wish was half a mile long).

With 300 million sperm contained in each man's ejaculation (that's the same number as the U.S. population), those sperm cells swim upstream with one gold-medal goal in mind-the egg. If unblocked by condoms or other barrier methods of birth control, they swim from the vagina and take the up escalator through the cervix to the uterus.

With a lot of luck, a special lining in the fallopian tubes that contains small hair-like structures are sucking the egg downward at the same time, so the sperm, like Alaskan salmon, have to swim upstream.

The thick-walled uterus is actually larger than a weightlifter's bicep and literally sucks on the penis and ultimately pulls the sperm into its chamber for fertilization. At that point, it's a dash to the finish to see which sperm cell can fertilize the egg first. If one does, the fertilized egg reaches an area of the uterine wall (womb) where it gets implanted.