Women’s Health

The endometrium of uterus is the innermost of three layers of uterus and consists of epithelial cells.

Cervical Endometrium:

The cervix is spindle shaped and measure about 2.5 cm and bounded by external os below and internal os above. The mucosal lining of cervical endometrium is different from that of the body of the uterus and the sub mucosa is absent in cervix. The cervix is lined by high columnar ciliated epithelium. The nuclei of the epithelium are spindle shaped and near the basement membrane. The direction of cilia is downwards and toward external os. The cervical endometrial glands are racemose type and secrete mucus which is rich in fructose. The secretion is alkaline and its high pH and fructose content make it attractive to ascending spermatozoa (male sperms). The secretions rich in sucrose and high pH collects in the cervical canal as a plug and probably stops the ascending infection. In gonorrhea the gonococcus are present in the crypts of the glands.

The external os is circular in nulliparous (woman who has not born a child) woman, but after vaginal delivery there is transverse slit of the external os, which is characteristic of parous (woman who has given birth) women.

The body of the uterus differs from that of cervix both structurally and functionally. Unlike epithelium of the body of the uterus the cervical epithelium does not show changes during menstrual cycle and also during pregnancy the cervical epithelium rarely changes, unlike the epithelium of the body of the uterus which undergo dramatic change in shape and size. The cancer of the body of the uterus is adenocarcinoma od the endometrium but that of the cervix is squamous cell carcinoma (cancer) type which is highly malignant.

There is an intermediate zone between endometrium of body and the mucous membrane of the cervix, known as the isthumus which is about 6 mm in length. The endometrium of the isthumus is anatomically and functionally similar to the body of the uterus. This isthmic portion forms the lower uterine segment in late pregnancy.

The relationship between the length of cervix and the body of the uterus varies according to age. The ratio of cervix to the body is 2:1 before puberty. At puberty the ratio reverses and become 1:2. During reproductive age the ratio is between, 1:3 to 1:4. After menopause the whole of the organ (uterus) atrophy.

The myometrium of the uterus is the middle muscle layer of the uterus and it is the thickest of the three layers of the uterus. The cervical part of myometrium is made up of plain muscle tissue with large amount of fibrous tissue that gives the hard consistency of the cervix. But the muscle fibers and fibrous tissues are mixed in with out any orderly fashion.

The myometrium is about 10-12 mm thickness in the body of the uterus. In the body of the uterus three layers of myometrium can be easily distinguished in pregnant uterus. The outermost layer is just below the peritoneum or perimetrium and it is longitudinal, the fibers passing from the cervix anteriorly over fundus and reaches backside of cervix. The layer can not be distinguished in non pregnant because it is thin. The main function of this layer is expulsion of fetus.

The middle layer is the thickest among three layers of myometrium and it consists of bundles of muscle fibers separated by connective tissue. The amount of connective tissue varies with age. The muscle content is much abundant during child bearing age (more during pregnancy) and much less before puberty and after menopause. The blood vessels which supply the uterus are distributed in the connective tissue of the middle layer. The blood vessel calibers depend on the contraction of the muscle of this layer. The function of this layer is expulsion of the fetus and hemostasis (control of bleeding). This layer is also called living ligature of the uterus and is responsible control of bleeding in the third stage of labour. Inefficient contraction of this layer is and retraction of this layer is responsible for postpartum hemorrhage (PPH)

The innermost layer of the myometrium consists of circular muscle fibers. The layer is not well marked, but is best represented in the opening of fallopian tubes and the internal os. The main function of the inner layer is to act like sphincter.

The perimetrium of uterus is the peritoneal lining and is the outermost layer of the uterus. The peritoneal lining of the uterus is incomplete. Front side of the whole body of the uterus is covered with peritoneum and the back of body of uterus is also covered with peritoneum. Anteriorly or in front side the peritoneum is reflected over the urinary bladder at the level of internal os and the whole of the cervix of uterus has no peritoneal lining in the front side.

Posteriorly or backside the perimetrium, the supravaginal portion of cervix is covered with peritoneal lining and from supra vaginal portion of uterus the peritoneal lining is reflected to the posterior fornix. On either side the peritoneal lining is incomplete due to insertion (joining) of fallopian tubes, the round ligaments and the ovarian ligaments into the uterus. Below the level of round and ovarian ligaments is the broad ligament which is formed by joining two sheets of peritoneum.