What do the ovaries do?

The ovaries have two main reproductive functions in the body. They produce oocytes (eggs) for fertilisation and they produce the reproductive hormones, oestrogen and progesterone. The function of the ovaries is controlled by gonadotrophin-releasing hormone released from nerve cells in the hypothalamus which send their messages to the pituitary gland to produce luteinising hormone and follicle stimulating hormone. These are carried in the bloodstream to control the menstrual cycle.

What hormones do the ovaries produce?

The major hormones secreted by the ovaries are oestrogen and progesterone, both important hormones in the menstrual cycle. Oestrogen production dominates in the first half of the menstrual cycle before ovulation, and progesterone production dominates during the second half of the menstrual cycle when the corpus luteum has formed. Both hormones are important in preparing the lining of the womb for pregnancy and the implantation of a fertilised egg, or embryo.



What could go wrong with the ovaries?


Any medical conditions that stop the ovaries functioning properly can decrease a woman’s fertility.

The ovaries naturally stop functioning at the time of menopause. This occurs in most women around the age of 50. If this happens earlier, before the age of 40, it is called premature ovarian failure or premature ovarian insufficiency.

The most common disorder of the ovaries is polycystic ovary syndrome which affects 5-10% of women of a reproductive age. In a polycystic ovary, the follicles mature to a certain stage, but then stop growing and fail to release an egg. These follicles appear as cysts in the ovaries on an ultrasound scan. Any abnormality which causes a loss of normal development of the ovaries, such as Turner syndrome, can result in the ovaries not functioning correctly and the loss of a woman’s fertility. The ovaries can be damaged by treatments for other conditions, particularly chemotherapy or radiotherapy for cancer treatment.

If a woman stops having menstrual periods during her reproductive years, this condition is called amenorrhoea. It can be caused by a number of factors. These include anorexia (an eating disorder which causes severe loss of body weight) and very low levels of body fat in athletes who train at a very high level. In these cases, fertility can be restored by weight gain and an increase in body fat. Disorders of the pituitary gland can affect normal ovarian function because a lack of the hormones normally released from the pituitary gland will reduce the stimulation of hormone production and the development of follicles in the ovaries. Thyroid over-activity (thyrotoxicosis) can lead to amenorrhoea, as can any severe illness.



Source: You and your hormones

http://www.yourhormones.info/glands/ovaries.aspx

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