Figure 1

Schematic of the cervical transformation zone. (Top) View of cervix as seen through gynecologist’s speculum showing ectocervix, TZ with Nabothian cysts, and endocervix. (Bottom) Cross section of transformation zone showing columnar epithelium of endocervix and stratified squamous epithelium of TZ and ectocervix. Nabothian cysts form when mucous ducts of endocervix become occluded by overgrowth of stratified squamous epithelium from newly formed TZ. Brown shading illustrates cells derived from endocervical reserve cells.