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Page 7
| of the uterus are not voluntary. The inner layer of the uterus is known as the endometrium. This is the layer that is rich in blood vessels. During the hormonal cycle, the endometrial lining enlarges in response to estrogen (as is discussed in the next chapter). Blood vessels in this layer eventually get deprived of blood, wither and eventually are shed as menstrual blood. If an egg is fertilized and enters the uterus, it will attach to the endometrium, and hormonal changes from that event will cause blood to continue to flow into the area so that the endometrium does not shed. It will, instead, be a source of enrichment and nourishment for the growing embryo. |
| The lower end of the uterus narrows to enter the vagina. The part of the uterus that extends into the vagina is known as the cervix. |
| The Cervix |
| The cervix is approximately 2.5 cm long. That portion of the uterus which extends into the vagina, the cervix has two openingsone at the uterine end called the internal os and one at the end that is visible in the vagina called the external os. The cells of the outside of the cervix are continually sloughed off into the vagina. A scraping of the cervix and vagina to obtain some of these cells is done in the procedure known as the Pap smear. Once placed on a slide, these cells are examined under microscope to be certain that they are normal. |
| Mucus is produced in the cervix and it changes with the hormonal changes of the normal reproductive cycle. This mucus can be examined in order to help determine where a woman is in her cycle and it can be used to aid in family planning by ensuring |
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