It is generally believed that women are born with a finite number of eggs. By puberty this number is expected to be around 250,000! Even though we likely only have a finite number of eggs, we have more than enough to accommodate our monthly use of a few of them over many many years. In fact, fewer than 500 oocytes are released in a woman's life time.
How do we use up our eggs? Each month in preparation for ovulation, the body selects several eggs, called oocytes, to continue their development, until one (and in rare cases, 2) oocyte is chosen to finish maturation. Ovulation occurs when that chosen oocyte is released from the ovary and made available for fertilization if there are sperm present.
As we approach menopause, our supply of eggs has diminished and ovulation may not occur on a monthly basis. Due to irregular ovulation and diminished fertile cervical mucus, conception may be more difficult if you are over 40 years old, but it is not impossible. Staying closely in tune with your fertility signals can help you time intercourse appropriately.
Freelance Contributor: Crystel Cortez
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Marieb E. Human Anatomy and Physiology. Seventh Edition. Benjamin Cummings: San Francisco, 2007. 1091-92.