At the same time, another egg matures. Once it is mature, it leaves the ovary and enters the fallopian tube. If the egg is not fertilized, it disintegrates, and the cycle continues. The length of the menstrual cycle may vary considerably, particularly among adolescents. Most menstrual cycles are between 21 and 40 days in length, with the average being 28 days.
Some girls notice emotional and physical changes during their menstrual cycles.
These changes are referred to as PMS premenstrual syndrome . Most women experience some of these changes but continue their normal activities. Any severe discomfort could be a signal that something is wrong. A girl should see a doctor if she experiences pain or unusual bleeding. Sperm Production Sperm are produced in two glands called testicles.