Endocervix – Tutorial
Please read Unit 13 – Introduction to Female Reproductive System Tissues prior to completing the activities in this chapter.
Introduction to the Cervix
The cervix is the most inferior region of the uterus that extends approximately 1-2 inches (2.5-5 cm) from the body of the uterus to the vagina. The constricted lumen of the cervix that extends from the inferior uterine cavity to the lumen of the vagina is known as the cervical canal. In a nonpregnant woman, the most distal portion of the cervix slightly bulges into the proximal lumen of the vagina forming a convex surface surrounding the external opening of the cervical canal known as the external os. The external os and the cervical canal act as the passageway for sperm to swim up into the uterine cavity after sexual intercourse and for fluid to exit the body during a woman’s menstrual period. When dilated during labor, the cervical canal and cervical os also act as a passageway for a fetus to leave the body during delivery.
The tutorials of this chapter will focus on the portion of the cervix known as the endocervix which is the inner portion of the cervix that surrounds the cervical canal. The walls of the endocervix that surround the cervical canal are lined with endocervical glands that secrete mucus into the lumen of the canal. During the majority of a woman’s menstrual cycle and during pregnancy, the endocervical glands secrete a thick mucus that acts as a barrier that blocks sperm and potential pathogens from moving up into the uterine cavity. Around the time when a woman is ovulating, the endocervical glands secrete a thinner mucus that allows sperm to swim up through the cervical canal into the uterine cavity.
The endocervical glands are deep infoldings of the cervical mucosa lined with densely packed mucus-secreting columnar cells. The wall of the endocervix does not possess the same muscular myometrium that other portions of the uterus possess. Instead, the myometrium of the endocervix is composed of fibroelastic connective tissue containing a combination of collagen and elastic fibers with relatively few smooth muscle cells. The fibroelastic tissue in the wall of the endocervix makes the wall extremely elastic which allows for excessive stretching during the delivery of a fetus.
