What Women Should Know About Their Ovaries

The ovaries are egg-producting glands that are part of the female reproductive system. The ovaries are about the size and shape of an almond and sit just above the fallopian tubes—one ovary on each side of the uterus. In a fertile person, every month during ovulation, either the right or left ovary produces a single mature egg for fertilization.

Woman consulting with her gynecologist in the gynecologist's office
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Ovarian Follicles

At birth, a female baby has about 1,000,000 ovarian follicles. Each ovarian follicle contains a hollow ball of cells with an immature egg in the center.

During childhood, approximately half of ovarian follicles are absorbed by the body. By the time of puberty and the beginning of an individual's menstrual cycle, only about 400,000 ovarian follicles are left to develop into mature eggs.

Although only one egg usually fully matures during ovulation, somewhere between 10 and 20 follicles begin the process of maturation monthly. The excess ovarian follicles are reabsorbed before ovulation occurs.


The process of ovulation is started and controlled by a drop in the hormone estrogen (mostly estradiol) and secretion of gonadotropin-releasing hormone (GnRH) thus sending a message to the pituitary gland to increase its secretion of follicle-stimulating hormone (FSH). The increase in FSH causes the growth of 10 to 20 of the ovarian follicles.

Estrogen is secreted by some of the cells in the follicle. Just before ovulation occurs, the follicle that contains the maturing egg eases toward the surface of the ovary. Once the matured egg reaches the ovarian surface, ovulation occurs when the follicle and the ovarian surface open allowing the egg to drift out of the ovary.

Additionally, progesterone is produced by the cells in the ovarian follicles shortly before ovulation occurs. After ovulation, if pregnancy has not occurred, the empty follicle is called the corpus luteum and it is reabsorbed into the body. If pregnancy does occur, the corpus luteum produces hormones that help to maintain the pregnancy.

After the egg is released from the ovary it travels to the oviducts (the funnel-shaped ends of the fallopian tubes) where it begins its long journey of several days into the uterus. The mature egg is moved along on its journey through the fallopian tubes by wavelike muscle contractions in the fallopian tube.

The inner lining of each fallopian tube contains cilia which are constantly beating microscopic hairs; these cilia are what help move the sperm towards the egg if a person has had unprotected sexual intercourse.

Conception (the fertilization of an egg with sperm) most often occurs in the part of the tubes that is nearest the ovary. Five to six days are required for the fertilized egg to reach the uterus.

Eggs that are not fertilized either disintegrate or flow out of the body (unnoticed) with vaginal secretions.

Midcycle Pain or Discomfort

You might experience a twinge, a cramp, or some discomfort in the lower back or abdomen when ovulation occurs. Some people notice a small amount of vaginal discharge, sometimes containing a small amount of blood, during ovulation.

For some people, these symptoms are severe enough to be mistaken for an ectopic pregnancy or appendicitis. Others experience headaches, gastric pain, or general malaise, while still others experience feeling much better during ovulation. These symptoms during ovulation are called mittelschmerz or midcycle pain.

Ovarian Cysts

Ovarian cysts are fluid-filled sacs, similar to blisters, that form on either of the ovaries. Ovarian cysts are common during the reproductive years. Most types of ovarian cysts are harmless and go away without any treatment.

Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a hormonal disorder that affects an estimated 7% of all women. It is the most common hormonal disorder among women. According to experts, the actual number of people affected by PCOS may be as high as 1 out of 10 simply because so many cases remain undiagnosed.

Why are so many cases of PCOS undiagnosed? Since the symptoms can vary from person to person it is often difficult to accurately diagnose it. Because polycystic ovary syndrome can cause significant long-term health consequences, a quick and accurate diagnosis, followed by proper treatment, is urgent.

Ovarian Cancer

Ovarian cancer is often called the "silent" killer because many times there are no symptoms until the disease has progressed to an advanced stage. In the U.S., ovarian cancer ranks fifth in cancer deaths among women, the highest rank for gynecological cancer deaths.

Fallopian Tube Damage

Fallopian tubes that have been damaged by diseases, infections, or other conditions may be scarred, damaged, or destroyed which sometimes can cause an ectopic (tubal) pregnancy to occur.

Some of the causes of fallopian tube damage include pelvic inflammatory disease (PID)endometriosis, or intrauterine devices (IUDs), as well as some sexually transmitted diseases (STDs) or other pelvic infections.

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  1. Cleveland Clinic. Mittelschmerz. Updated September 25, 2015.

  2. American College of Obstetricians and Gynecologists. Ovarian cysts. Updated April 2017.

  3. Wolf WM, Wattick RA, Kinkade ON, Olfert MD. Geographical prevalence of polycystic ovary syndrome as determined by region and race/ethnicityInt J Environ Res Public Health. 2018;15(11):2589. doi:10.3390/ijerph15112589

  4. American Cancer Society. Key statistics for ovarian cancer.

  5. American College of Obstetricians and Gynecologists. Pelvic inflammatory disease. Updated August 2019.