The Reproductive Process

What's What.
The uterus is a muscular organ in the lower abdomen. It is wide at the top and becomes narrow, like the neck of a bottle, at its lower end. Here, the cervix opens into the vagina. A fallopian tube extends outward from each side of the uterus. The ovaries are located on the sides of the uterus, near the fallopian tubes.

Each month, the endometrium-the lining of the uterus- builds up and sheds. An average menstrual cycle lasts about 28 days, counting from the first day (day 1 ) of one period to the first day of the next. A normal cycle can be shorter or longer than this, though, and may range from 23-35 days.

If an egg is not fertilized, it moves from the tube to the uterus and eventually is absorbed or disintegrates. Estrogen and progesterone levels decrease, and the lining of the uterus is shed as menstrual fluid on about day 28. The beginning of a menstrual period marks the start of a new cycle.

Menstrual fluid is made up of blood and tissue lining the uterus. Sometimes you may see blood clots. The volume of menstrual blood lost over one cycle usually amounts to only about 1/4 cup.

Source: Patient education material from the American College of Obstetrics and Gynecology was used as a source of information to develop the content for this topic.

Related Links