Histology
The epithelium of the cervix is varied. The ectocervix (more distal, by the vagina) is composed of nonkeratinized stratified squamous epithelium. The endocervix (more proximal, within the uterus) is composed of simple columnar epithelium.
The area adjacent to the border of the endocervix and ectocervix is known as the transformation zone. The Transformation zone undergoes metaplasia numerous times during normal life. When the endocervix is exposed to the harsh acidic environment of the vagina it undergoes metaplasia to squamous epithelium which is better suited to the vaginal environment. Similarly when the ectocervix enters the less harsh uterine area it undergoes metaplasia to become columnar epithelium.
Times in life when this metaplasia of the transformation zone occurs:
- puberty; when the endocervix everts (moves out) of the uterus
- with the changes of the cervix associated with the normal menstrual cycle
- post-menopause; the uterus shrinks moving the transformation zone upwards
All these changes are normal and the occurrence is said to be physiological.
However, all this metaplasia does increase the risk of cancer in this area - the transformation zone is the most common area for cervical cancer to occur.
At certain times of life, the columnar epithelium is replaced by metaplastic squamous epithelium, and is then known as the transformation zone.
Nabothian cysts are often found in the cervix.
Read more about this topic: Cervix