Uterus and Cervix PDF

Uterus and Cervix Dr. Moustafa Al Sawy 1. Histological structure of uterus 2. Endometrial changes in Menstrual cycle 3. Fertilization 4. Implantation and Placenta formation  UTERUS The uterus has three regions: fundus, body (corpus), and cervix. The uterine wall consists of the endomet...

Uterus and Cervix Dr. Moustafa Al Sawy 1. Histological structure of uterus 2. Endometrial changes in Menstrual cycle 3. Fertilization 4. Implantation and Placenta formation  UTERUS The uterus has three regions: fundus, body (corpus), and cervix. The uterine wall consists of the endometrium, myometrium, and external covering (adventitia or serosa) called perimetrium.  UTERUS 1. Endometrium The endometrium lined by a simple columnar epithelium containing secretory and ciliated cells. Under the epithelium there a connective tissue stroma contains many tubular glands. The endometrium undergoes cyclic changes during the menstrual cycle. Layers of the endometrium (According to the function) (1) The functional layer (functionalis) is the thick superficial layer of the endometrium that is sloughed and reestablished monthly because of hormonal changes during the menstrual cycle. (2) The basal layer (basalis) is the deeper layer of the endometrium that is preserved during menstruation. It has endometrial glands, which have basal cells that provide a source for reepithelialization of the functional layer. The endometrial vascular supply It consists of two types of arteries derived from vessels in the stratum vascularis of the myometrium. (1) Coiled arteries extend into the functional layer and undergo changes during various stages of the menstrual cycle. (2) Straight arteries do not undergo cyclic changes and terminate in the basal layer. Function of endometrium 1- Functional part of uterus for menstruation and reception of the ovum 2- Site of implantation and maturation of zygote 3- Site of maternal portion of placenta 4- Nutritive layer for embryo after pregnancy Myometrium The myometrium is the thick smooth muscle layer of the uterus. It is composed of inner and outer longitudinal layers and a thick middle circular layer. The circular layer is highly vascularized and is called stratum vascularis. The myometrium thickens during pregnancy due to hypertrophy and hyperplasia of their smooth muscle cells. Near the end of pregnancy, the myometrium develops many gap junctions between its smooth muscle cells. These junctions coordinate contraction of the muscle cells during delivery. At delivery, the myometrium undergoes powerful contractions triggered by the hormone oxytocin and by prostaglandins. After delivery, the myometrium will shrink due to sudden drop of estrogen that leads to apoptosis of many smooth muscle cells. External covering (Perimetrium) The perimetrium contains: A. Serosa is present over surfaces of the uterus bulging into the peritoneal cavity. B. Adventitia is present along the retroperitoneal surfaces of the uterus. Clinical correlation Endometriosis is a condition in which endometrial tissue grows outside the uterus. Endometriosis affects up to 10% of women between the ages of 15 and 44. It most often occurs on or around reproductive organs in the pelvis or abdomen, including the ovary. Endometrial tissue in abnormal sites does not shed during a menstrual cycle like healthy endometrial tissue inside the uterus does. The build up of abnormal tissue outside the uterus can lead to inflammation, scarring and painful cysts. Endometriosis is one of the most common cause of female infertility. Menstrual Cycle It begins on the first day of menstrual bleeding. It has 3 phases: 1. Menstrual phase (days 1–4) is characterized by a hemorrhagic discharge (menses) of the functional layer of the endometrium. It is triggered by vasoconstriction of the coiled arteries (caused by low levels of progesterone and estrogen) causes ischemia and necrosis of functional layer. Vasoconstriction is followed by sudden vasodilation of the coiled arteries causes their ruptures and dislodging the necrotic tissue with blood. Because the basal layer is supplied by short straight vessels that do not undergo prolonged vasoconstriction, it is not sloughed and does not become necrotic. The proliferative (follicular) phase days 4 to 14 The secretory (luteal) phase (days 15–28) It begins shortly after ovulation and is characterized by a thickening of the endometrium, resulting from edema and secretion by the endometrial glands. Glands become coiled; their lumen become filled with a secretion of glycoprotein material; and their cells accumulate large amounts of glycogen, in the basal aspect of their cytoplasm. Coiled arteries become not only more highly coiled but also longer, extending into the superficial aspects of the functional layer. Pregnant Endometrium - If fertilization and implantation occurs, embryonic trophoblast secrete HCG hormone, which stimulate corpus luteum to continue in secretion of progesterone to increase blood supply to endometrium, increase tortuosity of uterine glands and increase the interstitial fluid. - As a result, the menstrual cycle is stopped during duration of pregnancy II- Structure of the cervix The cervix does not participate in menstruation, but its secretions change during various stages of the menstrual cycle. The cervical wall is composed mainly of dense collagenous and elastic fibers with a few smooth muscle cells. It is the lower cylindrical part of the uterus that protrudes in vagina It is divided into:- Ectocervix (vaginal part) lined by stratified squamous epithelium. Endocervix (Supramarginal) surround cervical canal and lined by simple. columnar partially ciliated partially secretory but not slough during menstruation Cervical mucosa: It is formed of fibrous connective tissue and smooth muscle fibers containing mucosal glands (branched tubular glands) and affected functionally by hormonal changes during endometrial cycle. It secretes: 1- Serous fluid near the time of ovulation to facilitates the entry of spermatozoa into the uterine lumen. 2- Thick mucus secretion, during pregnancy, that hinders the entry of spermatozoa (and microorganisms) into the uterus. At labour, the cervix dilates and softens as a result of the lysis of the collagen fiber bundles in response to the relaxin hormone.  Clinical Correlation 1. In a Papanicolaou (Pap) smear, epithelial cells are scraped from the lining of the cervix (or vagina) and are examined to detect cervical cancer. A Pap smear shows variation in cell populations with stages of the menstrual cycle. 2. Carcinoma of the cervix originates from stratified squamous nonkeratinized epithelial cells. It may be contained within the epithelium and not invade the underlying stroma (carcinoma in situ), or it may penetrate the basal lamina and metastasize to other parts of the body (invasive carcinoma). It occurs at a relatively high frequency but may be cured by surgery if discovered early (by Pap smear), before it becomes invasive. UTERINE TUBES The uterine tubes (oviducts) measure about 10-12 cm in length. Each opens into the peritoneal cavity near the ovary. They have four parts: 1. Infundibulum, a funnel-shaped opening with fingerlike extensions called fimbriae next to the ovary. 2. Ampulla, the longest and expanded region were fertilization normally occurs. 3. Isthmus, a narrow portion nearer the uterus. 4. Intramural part, which passes through the wall of the uterus. The wall of the oviduct consists of: 1. Folded mucosa, 2. Masculosa is formed of inner circular and outer longitudinal layers of smooth muscle. 3. Serosa covered by visceral peritoneum with mesothelium. UTERINE TUBES The mucosa is lined by simple columnar epithelium on a lamina propria of loose connective tissue. The epithelium contains two types of cell types: 1. Ciliated cells in which ciliary movements sweep fluid toward the uterus. 2. Secretory peg cells, non-ciliated and often darker staining, often with an apical bulge into the lumen, which secrete glycoproteins of a nutritive mucus film that covers the epithelium. Clinical Correlations Tubal ligation is a common surgical type of contraception. Salpingitis is the inflammation of the uterine tube mucosa. Ectopic (tubal pregnancy: Mucosal damage or adhesions caused by chronic salpingitis can lead to infertility or an ectopic (tubal) pregnancy if there is blockage of fertilized ovum inside the tube. In tubal pregnancies, the lamina propria will act like the uterine endometrium, but because of the tubal lumen is small in diameter and unable to expand, the tube cannot tolerate the growing embryo and will rupture, causing potentially fatal hemorrhage. Clinical Scenario During the proliferative phase of the menstrual cycle, the functional layer of the endometrium undergoes which of the following changes? (A) Blood vessels become ischemic. (B) The epithelium is renewed. (C) The stroma swells because of edema. (D) Glands become coiled. (E) Blood vessels break down. Endometrial glands are typically most fully developed and filled with product during which day(s) or phase of a woman’s menstrual cycle? a. Menstrual phase b. Days 1-4 c. The day ovulation occurs d. Proliferative phase e. Days 15-28 Thank You