MHCY112 Cervix and Vagina PDF

Cervix and Vagina Female Reproductive System  Learning Objectives Describe the Female Reproductive System Review physiology and phases of Menstrual Cycle Describe the functions of Female Reproductive System Describe the morphological appearance of the cervix (epithelium & stroma) Descr...

Cervix and Vagina Female Reproductive System  Learning Objectives Describe the Female Reproductive System Review physiology and phases of Menstrual Cycle Describe the functions of Female Reproductive System Describe the morphological appearance of the cervix (epithelium & stroma) Describe the location of the squamo-columnar junction. Describe the morphological appearance of the vagina, including the various zones of stratified squamous epithelium. Describe the epithelium of the vagina of a normal adult, newborn, during pregnancy, puerperium, at post menopause & childhood.  Female Reproductive System Female Reproductive System includes the ovaries, the female genital tract and the breast (mammary glands) The ovaries start off the process – development and expulsion of the ova The ova move through the female genital tract starting with the winding fallopian tubes (oviducts) then on to the uterus, cervix, finally reaching the vagina # For understanding, it is important to study tissue with a review of reproductive (including endocrine) physiology. Menstrual Cycle Physiology Review Menstrual cycle proceeds through three distinct phases: Menstrual phase- Day 1-5 Proliferative phase- First half of Menstrual Cycle Secretory phase- Second half of Menstrual Cycle Menstrual phase Failure of fertilization and/ or implantation High progesterone levels lead to feedback inhibition of LH Corpus luteum involution Menstruation Follicular/ Proliferative phase This called the follicular phase in ovary & proliferative phase in the endometrium Up to day 14 (variable) Follicle stimulating hormone (FSH) lead to development of ovarian follicles Estrogen is rising due to changes in the ovary under the influence of FSH The uterine glands proliferate under the influence of estrogen There are many mitoses evident Ovulation- Midcycle Follicle Stimulating Hormone (FSH from anterior pituitary) & estrogen (from ovary) – peak just before ovulation (day 14) Higher estrogen secretion from the ovary stimulates the pituitary to produce more LH (LH surge) & inhibits the level of FSH Ovulation occurs as a result The remnants of the wall around the ruptured ovarian follicle becomes the corpus luteum under the influence of LH Luteal/ Secretory phase This called the luteal phase in ovary & secretory phase in the endometrium Progesterone at a higher level (secretions from the ovary) Higher progesterone levels sends a message to the pituitary gland to inhibit LH & the cycle begins again In the 2nd half, after ovulation, the glands of the endometrium become tortuous/convoluted & full of glycogen secretion in preparation for the fertilized egg If implantation doesn’t take place, the cycle begins again Female Reproductive System Surgical Specimen Fallopian Tubes Uterus Ovary Ovary Cervix Vaginal walls surrounding the cervix Functions of Female Reproductive System Production of ova (ovary) Reception of spermatozoa (vagina, cervix, uterus, fallopian tube) Provides an environment for fertilization (fallopian tube) Provides an environment for implantation of fertilized ova (uterus) Accommodates & nourishes the developing embryo (uterus) Parturition/ birth (uterus, cervix, vagina) Nutrition of newborn infant (breast) Basic histological stucture Basic histological structure: Mucosal lining (epithelium & lamina propria) Sub mucosa – LOCT Wall – generally includes a smooth muscle component  Cervix Normal cervix located at the lower part of the uterus  Cervix The main bulk of cervix is composed of collagenous tissue and a little smooth muscle Endocervix- The endocervix is the internal, canal-like portion of the cervix which opens into the uterus It has many epithelial folds that can expand during parturition The endocervix is lined by a single layer of tall columnar mucous secreting epithelial cells Ectocervix- The ectocervix is the portion of the cervix which is touchable and visible through the vaginal canal It is also called portio vaginalis (that portion of the uterus that lies within the vagina) The ectocervix is lined by thick stratified squamous epithelium Cervix External os- The point where the endocervical canal opens into the vagina (roughly at the junction of ectocervix and endocervix) Around the external os (opening) there is an abrupt transition from simple (tall) columnar epithelium of the endocervix to the stratified squamous non-keratinized (SSNK) epithelium of the exocervix or ectocervix SSNK epithelium of the cervix is continuous with that of the vagina  Functions of the Cervix To admit spermatozoa, provide access to the uterus Protects the uterus from bacterial invasion Tissues are capable of extreme stretching during childbirth Includes the opening from the uterus into the vagina (cervical os) Allows passage of menstrual blood to the vagina Is accessible for routine diagnostic examination (Pap test/smears) Is a site with special clinical significance (susceptible to cancer) Cervical cancer is associated with persistent Human Papilloma Virus (HPV) infection Cervical Stroma Cervical stroma (underlying the epithelium) is largely collagenous fibrous C.T., interwoven with smooth muscle There are no true “glands” beneath the epithelium in the exocervix (also called ectocervix) It’s the numerous folds present that may appear as glands when cut in cross section Connective Tissue Stroma muscle = pink collagen = pale orange Muscle Collagen Cervix 10X Endocervix with many folds Endocervix Endocervical Glands 10X (Simple Columnar Epithelium) Endocervical Glands 40X (Simple Columnar Epithelium) Endocervical Glands (Simple Columnar Epithelium) Squamo-columnar Junction Squamous metaplastic changes occur where the simple columnar epithelium is replaced by stratified squamous non-keratinized epithelium around the external os This area is called the transformation zone (Squmao columnar junction)  Squamo-columnar Junction – 4x Stratified squamous non-keratinized epithelium Simple columnar epithelium Cervix: Squamo-Columnar Junction  Squamo-Columnar Junction (green box) Notice the lack of mucous “glands” beneath the squamous epithelium Stratified Squamous Non- keratinized Epithelium  Squamo-Columnar Junction Stratified Squamous Non-keratinized Epithelium Simple Columnar Epithelium Connective Tissue Stroma Collagen and muscle fibers  Squamo-Columnar Junction Simple columnar epithelium Stratified squamous Non-keratinized epithelium There’s a fold in the tissue scan and it’s a bit blurry, difficult to see the actual S/C junction Exocervix- Stratified Squamous non-keratinized Epithelium Stratified Squamous Non-Keratinized Epithelium (relate to cells seen in a pap smear) Intermediate cells Superfical cells Basal cells – one layer thick Parabasal cells Nabothian Follicles Nabothian Follicles In the process of transformation zone formation, some invaginations or folds of columnar epithelium may be cut off from or lose their connection to the surface Continuing secretion at these sites by the simple columnar mucous secreting epithelial cells results in the formation of small Nabothian cysts or follicles Nabothian Follicles 10x- Lined by simple columnar epithelium Nabothian Follicle 40x Notice the simple columnar epithelial lining and mucous secretion Mucous is pale pink Nabothian Follicle Blood Vessels in Muscularis- Look for RBCs inside the lumen Vagina Essentially an elastic, muscular canal Epithelial lining serves protection Provides lubrication and sensation Connects the uterus to the outside world Vulva and labia form the entrance Cervix of the uterus protrudes into the vagina, forming the interior end Receives the penis during sexual intercourse Serves as a conduit for menstrual flow from the uterus During childbirth, the baby passes through the vagina (birth canal) Different appearance of the Vaginal Epithelium Thick stratified squamous non-keratinized epithelium in newborns, adults, pregnancy Thin stratified squamous non-keratinized epithelium in: Puerperium (after childbirth), childhood, postmenopausal women  Vagina- Mucosa and Submucosa Note: No mucous glands in the vagina – Lubrication comes from mucous secretion in the endocervix & labia minora - also from secretions of fluid transudate from the rich vascular network of the lamina propria  References and Useful Links Young B., O’Dowd, G., Woodford, P., Wheater's functional histology: A text and colour atlas. 6th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2014 Blue Histology – University of Western Australia http://www.lab.anhb.uwa.edu.au/mb140/big/big.htm Bowen, L., Histology of the Female Reproductive System, Module 053-2-AP, 2011 Revised Edition Southern Illinois School of Medicine: http://www.siumed.edu/~dking2/index.htm University of Iowa :Shotgun Histology Videos http://www.youtube.com/watch?v=IVQpqWYGdk8&feature=related University of Iowa – Virtual Slidebox: http://www.path.uiowa.edu/virtualslidebox/