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  • Writer's pictureLeanna Coy, FNP-C

Women’s Health 101: The Ovaries

Updated: Apr 23, 2023

This week for Women’s Health 101 let’s review the ovaries. The ovaries are part of the reproductive system for people assigned as females at birth. These little organs are a key component in pregnancy and hormone regulation.

Page of anatomy book showing internal organs


The ovaries are in the group of organs known as internal genitalia. Other parts of internal genitalia include the uterus, vagina, and fallopian tubes. In normal anatomy, there are two almond-shaped ovaries, one on each side of the uterus. The ovaries are the female gonads. This means they produce sex cells. In females, the sex cells are in the form of ova (eggs). The male equivalent of the ovaries is the testicles. The ovaries are much smaller than the testicles. On average each ovary is about 3 to 5 cm long and 2.5 cm wide - about the size of a grape. The size of the ovaries can change during the lifetime, including during different phases of the menstrual cycle. The ovaries attach to the uterus with ligaments and sit at the opening of the fallopian tubes.


There are two primary functions of the ovaries:

  1. The development and release of eggs

  2. The regulation of the female sex hormones

Development and release of eggs

The ovaries store the eggs in thousands of tiny sacs called follicles. The follicles help the eggs to mature. At birth, females are born with about 2 million eggs. Over a lifetime the number of eggs decreases at a steady state. By puberty, there are about 300,000 to 500,000 eggs. After puberty starts the number of eggs decreases by about 1000 every month. After age 35 even more are lost each month.

The ovaries choose which egg to release for possible fertilization into a fetus each month. Between puberty and menopause, the ovaries hold many eggs in various stages of development. A mature egg is released once a month in a process called ovulation. This is part of the menstrual cycle that occurs mid-cycle. In a lifetime about 400 to 500 eggs reach full maturity and are released for ovulation. The eggs that are not released for ovulation either fail to develop fully or deteriorate without maturing completely.

Releasing the female sex hormones

Male and female hormones are present in everyone. The average female body contains low levels of male hormones, known as androgens. The average male body contains a low level of female hormones, known as estrogens and progesterone. The ovaries control the release of estrogen and progesterone.

Estrogen is important in many bodily functions.

  • Helps regulate cholesterol

  • Keeps the bones strong

  • Triggers the development of breasts and reproductive organs

  • Regulates menstrual cycle

Progesterone is sometimes called the hormone of pregnancy due to its effects on pregnancy.

  • Prepares the uterus for a potential pregnancy by triggering the lining of the uterus to thicken

  • Prevents premature contractions

  • Prepares the uterus for labor

  • Prevents lactation until the fetus is born

Common health concerns for ovaries

Like most other organs, there are health issues that can affect the ovaries.

  • Polycystic ovarian syndrome (PCOS)

  • Endometriosis

  • Ovarian torsion

  • Premature menopause

  • Ovarian cancer


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