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Download Female Reproductive Cycle By Dr. Nand Lal Dhomeja
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FEMALE REPRODUCTIVE ORGANS LEARNING OBJECTIVES At the end of the lecture, student should be able to: Discuss the brief gross anatomy of each part of female genital system. Recognize the different parts of female genital tract and their location in pelvic cavity. State the blood supply, nerve supply and lymphatic drainage. Mention the microscopic features of each part in relation to ovulation, menstruation and pregnancy. Parts of Female Reproductive Organs Uterus Fallopian Tubes Ovaries Mammary Glands UTERUS Uterus The uterus (Latin [L.], womb) is a thick-walled, pear-shaped muscular organ Dimension averaging 7 to 8 cm in length, 5 to 7 cm in width at its superior part, 2 to 3 cm in wall thickness. The uterus consists of two major parts Body, the expanded superior two thirds Cervix, the cylindrical inferior one third Body of the uterus The body of the uterus narrows from the fundus, the rounded, superior part of the body, to the isthmus, the 1-cm-long constricted region between the body and cervix (L., neck). Cervix of the uterus The cervix of the uterus is its tapered vaginal end that is nearly cylindrical in shape. The lumen of the cervix, the cervical canal, has a constricted opening at each end. The internal os communicates with the cavity of the uterine body The external os communicates with the vagina Layers of Uterus The walls of the body of the uterus consist of three layers: Perimetrium, the thin external layer Myometrium, the thick smooth muscle layer Endometrium, the thin internal layer Perimetrium The perimetrium is a peritoneal layer that is firmly attached to the myometrium. Endometrium During the luteal (secretory) phase of the menstrual cycle, three layers of the endometrium can be distinguished microscopically : A thin, compact layer consisting of densely packed, connective tissue around the necks of the uterine glands . A thick, spongy layer composed of edematous connective tissue containing the dilated, tortuous bodies of the uterine glands . A thin, basal layer containing the blind ends of the uterine glands. At the peak of its development, the endometrium is 4 to 5 mm thick. The basal layer of the endometrium has its own blood supply and is not sloughed off during menstruation. The compact and spongy layers, known collectively as the functional layer, disintegrate and are shed during menstruation and after parturition (delivery of a baby). Uterine Tubes The uterine tubes, approximately 10 cm long and 1 cm in diameter, extend laterally from the horns (L., cornua) of the uterus. Each tube opens at its proximal end into the horn of the uterus and into the peritoneal cavity at its distal end. Parts of Fallopian Tube For descriptive purposes, the uterine tube is divided into four parts: the infundibulum • the ampulla the isthmus the uterine part Function of Fallopian tube The tubes carry oocytes from the ovaries and sperms entering from the uterus to reach the fertilization site in the ampulla of the uterine tube. The uterine tube also conveys the cleaving zygote to the uterine cavity. OVARIES The ovaries are almond-shaped reproductive glands located close to the lateral pelvic walls on each side of the uterus that produce oocytes. The ovaries also produce estrogen and progesterone, the hormones responsible for the development of secondary sex characteristics and regulation of pregnancy Vagina The vagina is a fibro muscular tubular tract leading from the uterus to the exterior of the body in female mammals The vagina is the place where semen from the anatomic male is deposited into the anatomically female person. BREASTS Organs of sexual arousal • Contain mammary glands • Consist of connective tissue that serves as support • Each breast contain 15-25 clusters called lobes • Each lobule is connected by ducts that open into the nipples • The nipples are made up of erectile tissue • The pigmented around the nipples are called the areola • Breast size is determined primarily by heredity • Size also depends on the existing fat and glandular tissue • Breasts may exhibit cyclical changes, including increased swelling and tenderness prior to menstruation • Benign breast changes refer to fibrocystic disease • Lumps or masses. Female Reproductive Cycle LEARNING OBJECTIVES: By the completion of the lecture, the student will be able to: – Define the female reproductive cycle( menstrual cycle) – Discuss its different phases – Interpret the hormonal control of menstrual cycle – Correlate the ovarian cycle and with menstrual cycle THE MENSTRUAL CYCLE: The menstrual cycle is the periodic vaginal bleeding that occurs with the shedding of the superficial layer Endometrium (menstruation). MENSTRUATION: The term menstruation (menstru = monthly) is used to indicate periodic shedding of the stratum functionale of the endometrium, which becomes thickened prior to menstruation under the control of ovarian steroid hormones. UTERUS: The wall of the uterus consists of three layers: A) Inner layer Endometrium or mucosa lining the inside wall. B) Middle layer Myometrium , a thick layer of smooth muscle C) Outer layer Perimetrium, the peritoneal covering lining the outside wall . DURATION OF THE CYCLE: Variable in women Typically an average figure is 28 days from the start of one menstrual period to the start of the next. It is convenient to call the first day of menstruation “day one” of the cycle. CYCLICAL CHANGES IN THE ENDOMETRIUM From puberty ( 11 to 13 years ) untill menopause ( 45 - 50 years ), the endometrium undergoes cyclical changes that occur approximately every 28 days and are under hormonal control by the ovary. From puberty ( 11 to 13 years ) untill menopause ( 45 - 50 years ), the endometrium undergoes cyclical changes that occur approximately every 28 days and are under hormonal control by the ovary. The uterine endometrium passes through three stages during the menstrual cycle: – follicular or proliferative phase, – Secretory or progestational phase, and – Menstrual phase. LAYERS OF ENDOMETRIUM: As a result three distinct layers can be recognized in the endometrium: – A superficial compact layer, – An intermediate Spongy layer, – And a thin basal layer. REGENERATION OF ENDOMETERIUM During the last menstural flow the Stratum Funtionalis shed off and the stratum basalis persists containing the basal (reserve cells). During the next cycle the stratum functionalis regenerates under influence of estrogen secreted from the corpus luteum in ovary . This is the beginning of proliferative phase. PROLIFERATIVE PHASE Lasts 9 days regeneration of stratum functional Formation of new blood vessels which are straight Formation of glands which are straight tubular This phase under the control of estrogen The thickness of stratum functional increases for 2-3 folds. SECRETORY OR PROGESTATIONAL PHASE: The secretory phase begins approximately 2 – 3 days after ovulation in response to progesterone produced by the corpus luteum. LUTEAL OR SECRETARY PHASE: Lasts for 13 days Under the control of progesteron secreted by corpus luteum The glands become wide, tortous & saccular They start to secrete glycogen rich material The arteries become coiled, the spiral arteries Venous network becomes complex & large lacunae developed Overall thickness of endomaterium increase INITIATION OF THE MENSTRAUL PHASE: If fertilization does not occur, then shedding of the endometrium (compact ad spongy ) begins, marking the initiation of the menstraul phase . When the menstrual phase begins, blood escapes from the superficial arteries, and small pieces of stroma and glands break away. During the following 3 or 4 days, the compact and spongy layers are expelled from the uterus, and the basal layer is the only part of the endometrium is retained. Basal layer is supplied by its own arteries, the basal arteries, and function as the regenerative layer in the rebuilding of glands and arteries in the proliferative phase. If fertilization does occur, then the endometrium assists in implantation and contributes to the formation of the placenta. At the time of implantation, the mucosa of the uterus is in the secretory phase, during which time uterine glands and arteries become coiled and the tissue becomes succulent. APPLIED ANATOMY Fallopian tube plays an important role in the mechanical transport and physiological sustenance of the gametes and early conceptus. Compromised tubal damage can occur after external or internal injury, inhibiting the normal transport of gametes. Pelvic inflammatory disease is a major clinically unsuspected reason for tubal subfertility. PID can damage the tube at multiple sites and also predispose to ectopic pregnancy.
