Development of the Transformation Zone
When a woman reaches puberty the cervix enlarges and undergoes a process known as eversion in response to ovarian hormones. The process of eversion results in a change in the position of the cervical epithelium so that epithelium initially lining the lower part of the cervical canal is situated on the vaginal part of the cervix.
This appears red since the capillary vasculature is seen through the single layer epithelium.
The image below demonstrates cervical ectopy