In this Article

• What parts make-up the female anatomy?
• What happens during the menstrual cycle?
• Follicular phase
• Ovulatory phase
• Luteal phase
• How many eggs does a woman have?
• Female Reproductive System Glossary
• Female Reproductive System Index

What Happens During the Menstrual Cycle?

Females of reproductive age experience cycles of hormonal activity that repeat at about one-month intervals. With every cycle, a woman's body prepares for a potential pregnancy, whether or not that is the woman's intention. The term menstruation refers to the periodic shedding of the uterine lining. (Menstru means "monthly"; hence the term menstrual cycle.)

The average menstrual cycle takes about 28 days and occurs in phases: the follicular phase, the ovulatory phase (ovulation), and the luteal phase.

There are four major hormones (chemicals that stimulate or regulate the activity of cells or organs) involved in the menstrual cycle: follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone.

Follicular Phase of the Menstrual Cycle

This phase starts on the first day of your period. During the follicular phase of the menstrual cycle, the following events occur:

• Two hormones, follicle stimulating hormone (FSH) and luteinizing hormone (LH) are released from the brain and travel in the blood to the ovaries.
• The hormones stimulate the growth of about 15 to 20 eggs in the ovaries each in its own "shell," called a follicle.
• These hormones (FSH and LH) also trigger an increase in the production of the female hormone estrogen.
• As estrogen levels rise, like a switch, it turns off the production of follicle-stimulating hormone. This careful balance of hormones allows the body to limit the number of follicles that mature.
• As the follicular phase progresses, one follicle in one ovary becomes dominant and continues to mature. This dominant follicle suppresses all of the other follicles in the group. As a result, they stop growing and die. The dominant follicle continues to produce estrogen.

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