The endocervical canal is lined with a moist mucous membrane. Cells within this tissue layer secrete fluids and project minute hairlike structures called cilia (cilium) that help to move sperm through the canal. The fluids given off consist mainly of water, sugars, starches, and proteins. During ovulation (when the ovaries release an egg) the mucous secretions are plentiful and watery; before and after ovulation the secretions are thick and relatively scant. The mucus is arranged in a meshlike pattern of filaments and spaces. During ovulation the openings in the meshwork of filaments become larger so that sperm may freely pass through. lysozyme, also present in cervical mucus, is an enzyme that helps to destroy certain types of bacteria and acts as a defense against infections.

Covering the mucous membrane is a thick layer of collagen and elastic fibres. There is also some muscle tissue, but the quantity is considerably less than in the rest of the uterus. The cervix is densely fibrous and, consequently, more rigid than the other uterine tissue. During pregnancy the cervix is the only part of the uterus that does not expand to house the developing child; the mucus inside the endocervical canal becomes very thick at this time and acts as a plug that helps to seal off the rest of the uterus from infection. Shortly before childbirth, the mucus thins, and the cervical walls relax to permit delivery.

Afflictions pertaining to the cervix include chronic inflammation, laceration and hemorrhaging during childbirth, malignant and benign tumours, and any of the many infectious venereal diseases.