Understanding the Function of Your Ovaries

A Summary of Your Ovaries' Role in Your Reproductive System

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The ovaries are a key part of the normal development and reproductive function of women. 

Anatomy of the Ovaries

Ovaries are a pair of glands (approximately the size and shape of an almond) in the female reproductive system where eggs are stored and estrogen is manufactured. They are held in place by several ligaments on either side of the uterus. Eggs are transported from the ovaries to the uterus via the fallopian tubes.

Surrounding the entrance to the fallopian tubes are tiny fimbrae, or finger-like projections, which guide the egg into the tube each month.

The Ovaries Through the Lifespan

A woman is born with all of the eggs she’ll ever need, around one million in each of the ovaries. By puberty, when she’ll most likely receive her first period, the number of eggs in each ovary is around 200,000 to 400,000. During her childbearing years, approximately 300 to 500 eggs will develop and be released during ovulation. After menopause, the ovaries will stop producing eggs, and atrophy (shrink). Due a loss of ovarian functioning and loss of estrogen production, postmenopausal women commonly experience symptoms like hot flashes and vaginal dryness. Estrogen deficiency also increases women's risks of developing osteoporosis, which increases their risk of bone fracture.

The Ovaries' Role in the Menstrual Cycle

While cycles may be irregular in the beginning, they will eventually become more regular with about 28 days between the first days of each period.

Each month, approximately 10 to 12 egg follicles will begin to develop. One will continue on to produce a mature egg. The rest will be reabsorbed into the ovarian tissue. About 14 days into a woman's cycle, that mature egg will be released in a process known as ovulation. After ovulation occurs, the empty follicle is known as a corpus luteum.

It will produce progesterone and other hormones crucial for pregnancy for about 14 days.

Progesterone helps prepare and thicken the lining of the uterus for implantation, if fertilization of the egg with sperm occurs. Also, if fertilization does occur, this hormonal support will continue throughout pregnancy to prevent other eggs from maturing. If fertilization does not occur, progesterone levels will decline, the corpus luteum will degenerate, and menstruation will begin.

Hormonal Role of the Ovaries

The ovaries are sensitive to the effects and changes of the endocrine or hormonal system. They respond to and produce their own hormones as needed by the body. In fact, the second major role of the ovary is to secrete the sex hormones -- estrogen, progesterone and very small amounts of androgens, which cause the typical female sex characteristics to develop and be maintained.

In addition, the ovaries also respond to FSH and LH which are produced by a small gland in the brain called the pituitary gland.

FSH, or follicle stimulating hormone, causes the estrogen level to rise and a group of egg follicles to grow each month. As one follicle becomes dominant and reaches maturity, the higher estrogen level will cause the LH (lutenizing hormone) to surge, triggering ovulation.

The Bottom Line

The ovaries and the hormones they produce (notably estrogen and progesterone) play a crucial function in a women's reproductive aging. 

Source:

The North American Menopause Society. (2014). The Menopause Practice: A Clinician’s Guide, 5th ed. Mayfield Heights, OH: The North American Menopause Society.

DISCLAIMER: The information in this site is for educational purposes only. It should not be used as a substitute for personal care by a licensed physician. Please see your doctor for diagnosis and treatment of any concerning symptoms or medical condition.

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