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The Menstrual Cycle

Hormonal interaction during the menstrual cycle includes hormones from the pituitary, the ovaries, and the uterus itself. In a complicated, interwoven pattern the hormones become dominant and retiring in turn, allowing ovulation (release of the ovum), fertilization, implantation (lodging of the fertilized egg on the wall of the womb), or menstruation, and then beginning over again.

The female reproductive organs are very susceptible to pathologic changes—those that constitute disease. Hormonal disruption can alter the cycle or stop it and other, as yet unknown causes can change cell development to a cancerous lesion. Also, at approximately 50 years of age, the woman undergoes what is commonly called the "change of life," or menopause. Here the hormonal pattern changes so that eggs no longer are produced and the menstrual cycle no longer takes place. Again, at this stage the woman is susceptible to long-term pathologic changes leading to osteoporosis (thinning of the bones), which renders her more likely to suffer fractures.

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Science EncyclopediaScience & Philosophy: Glucagon to HabitatGynecology - The Menstrual Cycle, Testing - History