It may surprise you to know that men don't have a monopoly on testosterone. Testosterone belongs to a class of male hormones called androgens. But women also have testosterone. The ovaries produce both testosterone and estrogen. Relatively small quantities of testosterone are released into your bloodstream by the ovaries and adrenal glands. In addition to being produced by the ovaries, estrogen is also produced by the body's fat tissue. These sex hormones are involved in the growth, maintenance, and repair of reproductive tissues. But that's not all. They also influence other body tissues and bone mass.

What are hormones? A hormone is a chemical substance. It's secreted by one tissue and travels by way of body fluids to affect another tissue in your body. In essence, hormones are "chemical messengers." Many hormones, especially those affecting growth and behavior, are significant to both men and women. The amount and levels of hormones change daily. The sex hormones, estrogen and testosterone, are secreted in short bursts -- pulses -- which vary from hour to hour and even minute to minute. Hormone release varies between night and day and from one stage of the menstrual cycle to another.

What is estrogen? Estrogen is an entire class of related hormones that includes estriol, estradiol, and estrone. Estriol is made from the placenta. It’s produced during pregnancy. Estradiol is the primary sex hormone of childbearing women. It is formed from developing ovarian follicles. Estradiol is responsible for female characteristics and sexual functioning. Also, estradiol is important to women's bone health. Estradiol contributes to most gynecologic problems, including endometriosis and fibroids and even female cancers. Estrone is widespread throughout the body. It is the main estrogen present after menopause.