The cervix is covered with a layer of skin-like cells on its outer surface, called the ectocervix. The results of your cervical screening test are based on the examination of the cells from the surface of the ectocervix. The test detects whether there are abnormal cells present.
Cells that are found in the cervical canal are called endocervical cells (glandular cells) these are different to the ectocervix. The transformation zone is the area from where the endocervix meets the ectocervix. This is where glandular cells normally change to squamous cells of the ectocervix. Rarely some women have endocervix cells that are abnormal and these abnormal areas are called glandular changes.
"Abnormal Cervical Cells and Treatment." Jo's Cervical Cancer Trust. N.p., 19 Aug. 2013. Web. 02 Mar. 2015.