Cervix Uteri

The cervix uteri (Latin: cervix uteri) is the lower fibromuscular segment of the uterus that is cylindrical or conical in shape, projecting into the lumen of the vagina and connecting it to the uterine cavity through the narrow cervical canal.

Etiology and pathophysiology

The cervix functions as a complex biological valve and immunological barrier. Cervical mucus contains lysozyme, lactoferrin, and secretory IgA, safeguarding the sterile uterine cavity from ascending infections. Histologically, the cervix comprises two zones:

1. Exocervix (vaginal portion): Covered with a robust, glycogen-rich, non-keratinizing stratified squamous epithelium.
2. Endocervix (canal): Lined with a single-layered columnar epithelium, producing mucus. The junction of epithelia (transformation zone) is an area of high mitotic activity and a site of persistence of the human papillomavirus (HPV), where dysplasia and cancer are initiated.

Clinical significance

Inflammation of the cervix (cervicitis) is an extremely common pathology. The anatomy of the epithelium determines infection tropism: gonococci and chlamydia affect the canal’s columnar epithelium, while herpes viruses and trichomonads affect the ectocervix’s squamous epithelium. During childbirth, the cervix undergoes structural reorganization (effacement and dilation up to 10 cm) to allow fetal passage. Isthmic-cervical insufficiency (weakness of the closure mechanism) is the primary cause of late miscarriages.