What Happened to All Those Eggs?

Baby girls enter the world with enough of them to populate perhaps 40 small cities. A dozen or so years later, the first will make a debut of its own. And in the months and years to come, others will appear regularly, sometimes greeted with relief, other times with disappointment, perhaps most often with a touch of annoyance.

Now, for women in the baby boom generation, they may be coming more sporadically, or not at all, signaling unmistakably that one time of life is over, and another begun. But what happened to all those eggs?

When girls are born, they have about two million eggs in their ovaries, nestled in fluid-filled cavities called follicles. That may sound like a lot, but consider that months earlier, when they were still in utero, they may have had as many as six or seven million eggs. Those eggs are still immature, and the proper name for them, by the way, is oocytes (rhymes with: nothing).

The first eggs to bite the dust were those in the fetus, which waste away. And by the time a girl reaches puberty, most of her remaining eggs have also deteriorated and been reabsorbed. If that sounds ominously like something from a “Star Trek” episode about the Borg, imagine if all those eggs had to take the customary path out of the body.

Even with the Great Egg Disappearance, girls enter puberty with many more than they will use, 300,000 or more. Each month, the body produces a hormone, FSH, which stimulates the follicles to prepare an egg for maturation and release.