This purpose of this study is to gain information about normal ovarian function that will be useful in developing a test for early detection of ovarian failure. The ovaries produce female hormones, such as estrogen, that are important in maintaining a woman's health. When the ovaries do not work properly, problems can develop. Unfortunately, there is no test that can detect ovarian failure early in its course. By the time premature ovarian failure is diagnosed in young women, two-thirds have already developed osteopenia (loss of some bone mass) and nearly one in ten have osteoporosis, a greater loss of bone mineral density that weakens bones and increases the risk of fractures.

Women with normal ovarian function ages 18 to 55 and postmenopausal women 60 years of age or older may be eligible for this study. Candidates will be screened with a medical history, physical examination, blood tests and vaginal ultrasound examination. For the ultrasound study, a probe that emits sound waves is inserted into the vagina, and the sound waves are converted to form images of the ovaries. The procedure is done with an empty bladder and takes about 10 minutes. After this screening visit (Visit 1), those enrolled in the study will return to the NIH Clinical Center for the following additional procedures:

Visit 2-Will be scheduled between days 3 and 5 of the menstrual cycle (for women who are still menstruating). Participants will have blood tests to measure hormone levels and to check for pregnancy, and will have another transvaginal ultrasound examination. They will then receive an injection of a synthetic form of follicle stimulating hormone (FSH), a hormone the body makes normally.

Visits 3 and 4-Will be scheduled 24 and 36 hours after the FSH injection given during Visit 2 for collection of blood samples.

Visit 5-Will be scheduled 48 hours after the FSH injection for additional blood sampling and a final transvaginal ultrasound examination.