It corresponds to a slight constriction known as the isthmus that can be seen on the surface of the uterus about midway between the apex and base.
Prior to pregnancy, the external orifice has a rounded shape when viewed through the vaginal canal (as through a speculum).
The wall of the canal presents an anterior and a posterior longitudinal ridge, from each of which proceed a number of small oblique columns, the palmate folds, giving the appearance of branches from the stem of a tree; to this arrangement the name arbor vitae uteri is applied.
The cervical canal is generally lined by "endocervical mucosa" which consists of a single layer of mucinous columnar epithelium.
Endocervical adenocarcinoma, like cervical cancer (squamous cell carcinoma), often arises in the milieu of human papillomavirus infection.