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Female Reproductive System Consists of: Ovaries ((Testes in Males)) Fallopian tubes ((Conductive Tube)) Uterus Vagina Bartholin’s glands Vulva breasts Female Reproductive System The female genital organs consist of an internal and an external group. The internal organs are situated within the pelvis, and consist of the ovaries, the uterine tubes, the uterus, and the vagina. The external organs are placed below the urogenital diaphragm and below and in front of the pubic arch. They comprise the mons pubis, the labia majora et minora pudendi, the clitoris, the bulbus vestibuli, and the greater vestibular glands. Ovaries Are Homologous With The Testes In The Male. They are two nodular bodies, situated one on either side of the uterus in relation to the lateral wall of the pelvis, and attached to the back of the broad ligament of the uterus, behind and below the uterine tubes . The ovaries are of a grayish-pink color, and present either a smooth or A Puckered Uneven Surface. They are each about 4 cm. in length, 2 cm. in width, and about 8 mm. in thickness, and weigh from 2 to 3.5 gm. Each ovary lies in a shallow depression, named the Ovarian Fossa, on the lateral wall of the pelvis; this fossa is bounded Above By The External Iliac Vessels, in front by the obliterated umbilical artery, and Behind By The Ureter. Female Reproductive System The Ovaries The ovaries function in: Development and ovulation of oocytes The production and secretion of hormones. The Ovary Is Attached To The Broad Ligament By A Short Fold Of Peritoneum, Called The Mesovarium through which Vessels And Nerves pass to the ovary and enter it at the hilus of the ovary. The surface of the ovary is covered by a single layer of Cuboidal Epithelium, also called Germinal Epithelium. It is continuous with the peritoneal mesothelium. It is covered by a capsule of Fibrous connective tissue, the Tunica Albuginea, immediately beneath the epithelium. Female Reproductive The female gonads or sex glands System 1. Ovaries 2 Almond Sized Glands, either side of uterus A woman is born with about 400,000 immature eggs called Primordial follicles During a lifetime a woman releases about 400 to 500 fully matured eggs for fertilization The follicles in the Ovaries Produce The Female Sex Hormones, Progesterone And Estrogen These hormones prepare the uterus for implantation of the fertilized egg Ovaries The exact position of the ovary is variable . The ovary becomes displaced during the first pregnancy, and probably never again returns to its original position. In the erect posture the long axis of the ovary is vertical. The Tubal Extremity is near the external iliac vein; attached the Suspensory Ligament Of The Ovary. The Uterine End is directed downward toward the pelvic floor, it is usually narrower than the tubal, and Is Attached To The Lateral Angle Of The Uterus by a rounded cord termed The Ligament Of The Ovary, which lies within the broad ligament. 1. Ovaries Each ovary is held in place by 3 ligaments: Broad ligament: suspends ovaries between the uterus & pelvic wall Ovarian ligament: attaches ovaries to the uterus Suspensory ligament: attaches ovaries to the pelvic wall Ovary Vessels and Nerves. The arteries of the ovaries and uterine tubes are the Ovarian From The Aorta. Each anastomoses freely in the mesosalpinx, with the Uterine Artery, giving some branches to the uterine tube, and others which traverse the mesovarium and enter the hilum of the ovary. The Veins emerge from the hilum in the form of a plexus, the Pampiniform Plexus; the OVARIAN VEIN IS FORMED FROM THIS PLEXUS, and leaves the pelvis in company with the artery. The Nerves are derived from the Hypogastric Or Pelvic Plexus, And From The Ovarian Plexus. Ovary Histology The ovary is divided into An Outer Cortex And An Inner Medulla. The cortex consists of Connective Tissue Stroma in which the Ovarian Follicles are embedded. The medulla is composed of Loose Connective Tissue, which contains blood vessels and nerves. Ovarian Follicles Ovarian follicles consist of one oocyte and surrounding follicular cells. Follicular development can be divided into a number of stages. Development represents a morphological continuum, that starts at Puberty And Continues Till Meopause. Ovarian Follicles • • • Ovarian follicles consist of one oocyte and surrounding follicular cells. Follicular development can be divided into a number of stages. Development represents a morphological continuum, and it may not be possible to assign all follicles to a specific stage. This said, it's pretty easy most of the time. Primordial Follicles are located in the cortex just beneath tunica albuginea. One Layer Of Flattened Follicular Cells surround the oocyte (about 30 µm in diameter). The nucleus of the oocyte is positioned eccentric in the cell. It appears very light and contains a prominent nucleolus. Most organelles of the oocyte aggregate in the centre of the cell, where they form the vitelline body (probably not visible in any of the available preparations). Ovary At birth, many oogonia are invested by flattened follicle cells = Primary Ovarian Follicle ((Primordial Follicles)). At maturity, upon stimulation (FSH) follicle cells enlarge and divide forming a Stratified Cuboidal Epithelial Layer = Membranosa Granulosa, with a hollow fluid filled cavity = Antrum. The ovum is suspended in the center Of The Antrum On A Hillock Of Granulosa Cells = Cumulus Oophorus. The developing ovum is surrounded by a layer of follicle cells (Corona Radiata = stratified cuboidal epithelium) and these two bodies secrete an amorphous ring the Zona Pellucida around the ovum. Oogenesis • • • Secondary Follicle Small Fluid-filled spaces become visible between the granulosa cells as the follicle reaches a diameter of about 400 µm. These spaces enlarge and fuse to form the Follicular Antrum, which is the Defining Feature Of The Secondary Follicle. The oocyte is now located eccentric in the follicle in the cumulus oophorus, where it is surrounded by granulosa cells. The Theca Folliculi Differentiates with the continued growth of the follicle into a Theca Interna And A Theca Externa. Vascularization of the theca interna improves, and the spindle-shaped or polyhedral cells in this layer start to PRODUCE OESTROGENS. The Theca Externa Retains the characteristics of a highly cellular connective tissue with Smooth Muscle Cells. The oocyte of the secondary follicle reaches a diameter of about 125 µm. The follicle itself reaches a diameter of about 10-15 mm. Oocyte • The Zona Pellucida The Oocyte outer membrane(glycoproteins between interdigitating processes of oocyte and granulosa cells) becomes visible. Parenchymal cells of the ovary surrounding the growing follicle become organised in concentric sheaths, the theca folliculi. Oogenesis • The mature or tertiary or preovulatory Or Graafian Follicle increases further in size (in particular in the last 12h before ovulation). The Graafian follicle forms a small "bump" on the surface of the ovary, the stigma (or macula pellucida). The stigma is characterised by a thinning of the capsule and a progressive restriction of the blood flow to it. Prior To Ovulation The Cumulus Oophorus Separates From The Follicular Wall. The Oocyte Is Now Floating Freely In The Follicular Antrum. It is still Surrounded By Granulosa Cells which form the corona radiata. The follicle finally ruptures at the stigma and the oocyte is released from the ovary. Reproduction and the Menstrual Cycle The egg cell is fertile for about 24-48 hours after ovulation In general, fertilization occurs 14th and 15th days. Sperm cells are fertile in the reproductive tubes for about 48-72 hours. The Corpus luteum • • • The corpus luteum is formed by Both Granulosa Cells And Thecal Cells After Ovulation Has Occurred. The wall of the follicle collapses into a folded structure, which is characteristic for the corpus luteum. Vascularization Increases and a connective tissue network is formed. Theca interna cells and granulosa cells triple in size and start accumulating lutein (Which hormone stimulates this process? Where is this hormone produced?) within a few hours after ovulation. They Are Now Called Granulosa Lutein Cells And Theca Lutein Cells And Produce Progesterone And Oestrogens. Hormone secretion in the corpus luteum ceases within 14 days after ovulation if the Oocyte Is Not Fertilised. In this case, the corpus luteum degenerates into a Corpus Albicans - whitish scar tissue within the ovaries. Hormone secretion continues for 2-3 month after ovulation if fertilization occurs till FORMATION OF PLACENTA . Atresia Is the name for the degenerative process by which oocytes (and follicles) perish without having been expelled by ovulation. about 99.9 % of the oocytes that where present at the time of puberty undergo atresia. Atresia may effect oocytes at all stages of their "life" - both prenatally and postnatally. By the sixth month of gestation about 7 million oocytes and oogonia are present in the ovaries. By the time of birth this number is reduced to about 2 million. Of these only about 400.000 survive until puberty. Atresia is also the mode of destruction of follicles whose maturation is initiated during the cyclus (10-15) but which do not ovulate. Atresia is operating before puberty to remove follicles which begin to mature during this period (none of which are ovulated). Given that atresia affects follicles at various stages of their development it is obvious that the process may take on quite a variety of histological appearances. Fallopian tubes ◦ ◦ ◦ ◦ ◦ ◦ 2 Tubes, 5 Inches Long Attached To The Upper Part Of The Uterus Lateral ends found above the ovaries and not directly connected Fingerlike projections called Fimbriae that help move ovum into the fallopian tube Serves as passage for ovum from the ovary to the uterus Ovum moved by peristalsis Cilia Assist released Mature Oocyte movement toward the uterus Fertilization ◦ ◦ Union of the ovum and sperm to create a new life Takes place in the fallopian tube in the Ampullary Region Fallopian Tube/Oviduct The oviduct functions as a conduit for the oocyte, from the ovaries to the uterus. Histologically, the oviduct consists of a mucosa and a muscularis .The peritoneal surface of the oviduct is lined by a serosa and subjacent connective tissue. The mucosa is formed by A CILIATED/NON CILIATED COLUMNAR EPITHELIUM AND SECRETORY EPITHELIUM resting on a very cellular lamina propria. The number of ciliated cells and secretory cells varies along the oviduct. Secretory activity varies during the menstrual cycle .Some of the secreted substances are thought to nourish the oocyte and the very early embryo. The muscularis consists of an inner circular muscle layer and an outer longitudinal layer. An inner longitudinal layer is present in the isthmus and the intramural part of the oviduct. PERISTALTIC MUSCLE action seems to be more important for the transport of sperm and oocyte than the action of the cilia. The Uterine Tubes They are two in number, one on either side, situated in the Upper Margin Of The Broad Ligament, And Extending From The Superior Angle Of The Uterus To The Side Of The Pelvis. Each tube is about 10 cm. long, and is described as consisting of three portions: (1) ISTHMUS, or medial constricted third; (2) AMPULLA, or intermediate dilated portion, which curves over the ovary; and (3) INFUNDIBULUM with its abdominal ostium, surrounded by fimbriæ, one of which, the ovarian fimbria is attached to the ovary. The Uterine Tubes Fertilization of the ovum is believed to occur in the Ampulla eht fo tube, and the fertilized ovum is then normally passed on into the uterus; the ovum, however, may Adhere To And Undergo Development In The Uterine Tube. (Chronic Smoking), Giving Rise To The Commonest Variety Of Ectopic Gestation. In such cases the amnion and chorion are formed, but a true decidua is never present; and the gestation usually ends by 2 months leading to Rupture of the Oviduct. The Uterus is a hollow, thick-walled, muscular organ situated deeply in the pelvic cavity between the bladder and rectum. Into its upper part the uterine tubes open, one on either side, while below, its cavity communicates with that of the vagina. In The Virgin State the uterus apex directed downward and backward. It lies between the bladder in front and the pelvic or sigmoid colon and rectum behind, and is completely within the pelvis. After parturition the uterus returns almost to its former condition, but certain traces of its enlargement remains. The Uterus The uterus measures about 7.5 Cm. In Length, 5 Cm. In Breadth, At Its Upper Part, And Nearly 2.5 Cm. In Thickness; It Weighs From 30 To 40 Gm. The total length of the uterine cavity from the external orifice to the fundus is about 6.25 cm. It is divisible into two portions. On the surface, about midway between the apex and base, is a slight constriction, known as the Isthmus, and corresponding to this in the interior is a narrowing of the uterine cavity, the internal orifice of the uterus. The portion above the isthmus is termed the Body, and that below, the Cervix. The part of the body which lies above a plane passing through the points of entrance of the uterine tubes is known as the Fundus. Clinical Aspect A retroverted uterus (tilted uterus, tipped uterus) is a Uterus that is tilted backwards instead of forwards. This is in contrast to the slightly ”Anteverted" uterus that most women have, which is tipped forward toward the Bladder, with the anterior end slightly concave. The Uterus Body anterior surface is covered by peritoneum, which is reflected on to the bladder to form the vesicouterine pouch. The surface lies in apposition with the bladder. The Posterior Surface is covered by peritoneum, which is continued down on to the cervix and vagina. It is in relation with the sigmoid colon. The fundus is covered by peritoneum continuous with that on On it rest some coils of small intestine, and occasionally the distended sigmoid colon. The lateral margins where the uterine tube pierces the uterine wall. Below and in front of this point the Round Ligament Of The Uterus Is Fixed, While Behind It Is The Attachment Of The Ligament Of The Ovary. These three structures LIE WITHIN A FOLD OF PERITONEUM which is reflected from the margin of the uterus to the wall of the pelvis, and is named the BROAD LIGAMENT. Cervix The cervix is the lower constricted segment of the uterus. It is somewhat conical in shape, with its truncated apex directed downward and backward The long axis of the cervix is therefore seldom in the same straight line as the long axis of the body. The long axis of the uterus as a whole presents the form of a curved line with its concavity forward, or in extreme cases may present an Angular Bend At The Region Of The Isthmus. The cervix projects through the anterior wall of the vagina, which divides it into an upper, supravaginal portion, and a lower, vaginal portion. Cervix The posterior vaginal wall, is reflected on to the rectum, forming the rectouterine Pouch. The vaginal portion of the cervix projects free into the anterior wall of the vagina between the anterior and posterior fornices. On its rounded extremity is a small, depressed, somewhat circular aperture, the external orifice of the uterus, through which the cavity of the cervix communicates with that of the vagina. Ligamentous Support Round Ligament: Fibrous and muscle tissue Anterior to the fallopian tubes Correlate with the male gubernaculums They Extend Laterally, Cross The External Iliac Vessels, And Enter The Internal Inguinal Ring, And Insert In The Labia Majora. a branch of the uterine artery, runs along the length of the round ligament. Ligamentous Support Broad Ligament: Double reflection of the peritoneum, draped over the round ligaments. Cardinal Ligament: Found at the base of the broad ligament. Provides the main support for the uterus and cervix. It Attaches To The Cervix And Extends Laterally, Connecting To The Endopelvic Fascia. Ligamentous Support Uterosacral Ligaments: Provide minor cervical support. Originate from the Upper Posterior Cervix, Travel Around The Rectum Bilaterally, And Fan Out To Attach To The 1st - 5th Sacral Vertebrae. Uterine Ligaments The ligaments of the uterus are eight in number: one anterior; one posterior; two lateral or broad; two uterosacral; and two round ligaments. The anterior ligament consists of the vesicouterine fold of peritoneum, which is reflected on to the bladder from the front of the uterus, at the junction of the cervix and body. The posterior ligament consists of the rectovaginal fold of peritoneum, which is reflected from the back of the posterior fornix of the vagina on to the front of the rectum. It forms the bottom of a deep pouch called the rectouterine Pouch, which is bounded in front by the posterior wall of the uterus, the supravaginal cervix, and the posterior fornix of the vagina; behind, by the rectum; and laterally by two crescentic folds of peritoneum which pass backward from the cervix uteri on either side of the rectum to the posterior wall of the pelvis. These folds are named the sacrogenital or rectouterine folds. They contain a considerable amount of fibrous tissue and non-striped muscular fibers which are attached to the front of the sacrum and constitute the uterosacral ligaments. The two lateral or broad ligaments pass from the sides of the uterus to the lateral walls of the pelvis. Together with the uterus they form Uterine Ligaments a septum across the female pelvis, dividing that cavity into two portions. In the anterior part is contained the bladder; in the posterior part the rectum, and in certain conditions some coils of the small intestine and a part of the sigmoid colon. Between the two layers of each broad ligament are contained: (1) the uterine tube superiorly; (2) the round ligament of the uterus; (3) the ovary and its ligament; (4) the epoöphoron and paroöphoron; (5) connective tissue; (6) unstriped muscular fibers; and (7) bloodvessels and nerves. The portion of the broad ligament which stretches from the uterine tube to the level of the ovary is known by the name of the mesosalpinx. Between the fimbriated extremity of the tube and the lower attachment of the broad ligament is a concave rounded margin, called the infundibulopelvic ligament. Uterine Ligaments The round ligaments (ligamentum teres uteri) are two flattened bands between 10 and 12 cm. in length, situated between the layers of the broad ligament in front of and below the uterine tubes. Commencing on either side at the lateral angle of the uterus, this ligament is directed forward, upward, and lateralward over the external iliac vessels. It then passes through the abdominal inguinal ring and along the inguinal canal to the labium majus, in which it becomes lost. The round ligaments consists principally of muscular tissue, prolonged from the uterus; also of some fibrous and areolar tissue, besides bloodvessels, lymphatics; and nerves, enclosed in a duplicature of peritoneum, which, in the fetus, is prolonged in the form of a tubular process for a short distance into the inguinal canal. This process is called the canal of Nuck. It is generally obliterated in the adult, but sometimes remains pervious even in advanced life. It is analogous to the saccus vaginalis, which precedes the descent of the testis. In addition to the ligaments just described, there is a band named the ligamentum transversalis colli (Mackenrodt) on either side of the cervix uteri. It is attached to the side of the cervix uteri and to the vault and lateral fornix of the vagina, and is continuous externally with the fibrous tissue which surrounds the pelvic bloodvessels. The form, size, and situation of the uterus vary at different periods of life and under different circumstances. Vessels and Nerves The arteries of the uterus are the uterine, from the hypogastric; and the ovarian, from the abdominal aorta. They are remarkable for their tortuous course in the substance of the organ, and for their frequent anastomoses. The termination of the ovarian artery meets that of the uterine artery, and forms an anastomotic trunk from which branches are given off to supply the uterus, their disposition being circular. Uterine Blood & Nerve Supply The veins are of large size, and correspond with the arteries. They end in the uterine plexuses. In the impregnated uterus the arteries carry the blood to, and the veins convey it away from, the intervillous space of the placenta. The lymphatics follow the course of arteries. The nerves are derived from the Hypogastric And Ovarian Plexuses, And From The Third And Fourth Sacral Nerves. The vagina Extends from the vestibule to the uterus, and is situated behind the bladder and in front of the rectum; it is directed upward and backward, its axis forming with that of the uterus an angle of over 90°, opening forward. Its walls are ordinarily in contact, Collapsed. Its length is 6 to 7.5 cm. along its anterior wall, and 9 cm. along its posterior wall. It surrounds the vaginal portion of the cervix uteri, a short distance from the external orifice of the uterus, its attachment extending higher up on the posterior than on the anterior wall of the uterus. To the recess behind the cervix the term posterior fornix is applied, while the smaller recesses in front and at the sides are called the anterior and lateral fornices. Vagina Relations.—The anterior surface of the vagina is in relation with the Fundus Of The Bladder, And With The Urethra. Upper ¼ Its Posterior Surface Is Separated From The Rectum By The Rectouterine Pouch Mid 2/4 by the Rectovesical Fascia Lower Fourth Is Separated From The Anal Canal By The Perineal Body. Its Sides Are Enclosed Between The Levatores Ani Muscles. The vagina The erectile tissue consists of a layer of loose connective tissue, situated between the mucous membrane and the muscular coat; imbedded in it is a plexus of large veins, and numerous bundles of unstriped muscular fibers, derived from the circular muscular layer. The arrangement of the veins is similar to that found in other erectile tissues. The Uterus The uterus is divided into body( upper two-thirds )and cervix .The walls of the uterus are composed of: mucosal layer, the endometrium ,and a fibromuscular layer, the myometrium . The peritoneal surface of the uterus is covered by a serosa. MYOMETRIUM The muscle fibres of the uterus form layers with preferred orientations of fibres( actually 4 ,)but this is very difficult to see in most preparations. The muscular tissue hypertrophies during pregnancy, and GAP-junctions between cells become more frequent. Endometrium The endometrium consists of a Simple Columnar Epithelium (ciliated cells and secretory cells) and an underlying Thick Connective Tissue Stroma. The mucosa is invaginated to form many simple tubular UTERINE GLANDS .The glands extend through the entire thickness of the stroma. The stromal cells of the endometrium are embedded in a Network Of Reticular Fibres. The endometrium is subject to Cyclic Changes That Result In Menstruation. Only the mucosa of the body of the uterus takes part in the menstrual cycle. Uterus The endometrium can be divided into two zones based on their involvement in the changes during the menstrual cycle: THE BASALIS AND THE FUNCTIONALIS. The BASALIS is not sloughed off during menstruation but functions as a regenerative zone for the functionalis after its sloughing during menstruaion. The FUNCTIONALIS IS THE LUMINAL part of the endometrium. It is sloughed off during every menstruation and it is the site of cyclic changes in the endometrium. These cyclic changes are divided into a number of phases: Proliferative (Or Follicular), Secretory (Or Luteal), And Menstrual. Pap-smear Cell coloured using the method invented by George Papanicolaou (1883-1962) Squamo-columnar junction Examples Pap I: normal cells 1=superficial cells 2=intermediate cells Pap II: inflammatory cells with Trichomonas (3) Cervix carcinoma Cervical cancer is the most common malignant genital cancer of women Cancerogenesis: Normal epithelium Precancerosis (not invasive) Dysplasias years Carcinoma in situ years Cancer Cancer years 20-35 25-40 45-55 Stratum superficiale Stratified squamous epithelium Stratum spinosum Stratum basale Basal lamina Connective tissue Dysplasia Carcinoma in situ Cell classes Vagina The vagina is a fibromuscular tube with a wall consisting of three layers: the mucosa, muscularis and adventitia of the vagina Mucosa Muscularis The stratified squamous epithelium (deep stratum basalis, intermediate stratum spinosum, superficial layers of flat eosinophilic cells which do contain keratin but which do not normally form a true horny layer) rests on a very cellular lamina propria (many leukocytes). Towards the muscularis some vascular cavernous spaces may be seen (typical erectile tissue.) Inner circular and outer longitudinal layers of smooth muscle are present. Inferiorly, the striated, voluntary bulbospongiosus muscle forms a sphincter around the vagina. Adventitia The part of the adventitia bordering the muscularis is fairly dense and contains many elastic fibres. Loose connective tissue with a prominent venous plexus forms the outer part of the adventitia. Female Accessory Reproductive Glands Mammary Glands The mammary glands are modified glands of the skin. Their development resembles that of sweat glands. They are compound BRANCHED ALVEOLAR GLANDS, which consist of 15-25 lobes separated by dense interlobar connective tissue and fat. Each lobe contains an individual gland. The excretory duct of each lobe, also called LACTIFEROUS DUCT ,has its own opening ON THE NIPPLE. The secretory units are ALVEOLI, which are lined by a CUBOIDAL OR COLUMNAR EPITHELIUM . A layer of MYOEPITHELIAL CELLS is always present between the epithelium and the basement membrane of the branches of the lactiferous duct and the alveoli. Ovarian Cycles After puberty the ovary cycles between a Follicular Phase (Maturing Follicles) and a Luteal Phase (Presence Of The Corpus Luteum). These cyclic phases are interrupted only by pregnancy and continue until menopause, when reproductive capability ends. The ovarian cycle lasts usually 28 days. During the first phase, the oocyte matures within a follicle. At midpoint of the cycle, the oocyte is released from the ovary in a process known as OVULATION. Following ovulation the follicle forms a corpus luteum which synthesizes and prepares Hormones To Prepare The Uterus For Pregnancy. The mature oocyte passes into the oviduct (fallopian tube or uterine tube). The oviduct is connected to the uterus. The uterus has an inner layer, the endometrium, in which a fertilized egg IMPLANTS. Hormones and Female Cycles • • • The ovarian cycle is Hormonally Regulated in TWO PHASES. Hormones from the Hypothalamus And Anterior Pituitary control the ovarian cycle. The follicle secretes Estrogen Before Ovulation; the Corpus Luteum Secretes Both Estrogen And Progesterone After Ovulation. The ovarian cycle covers events in the ovary; the menstrual cycle occurs in the uterus. The first day of the cycle is the first day of blood flow (Day 0) known as menstruation. During menstruation the Uterine Lining Is Broken Down and Shed As Menstrual Flow. FSH and LH are secreted on day 0, beginning both the Menstrual Cycle And The Ovarian Cycle. Both FSH and LH stimulate the Maturation Of A Single Follicle in one of the ovaries and the secretion of estrogen. Rising levels of Estrogen In The Blood trigger secretion of LH, which stimulates FOLLICLE MATURATION and ovulation (day 14, or midcycle). LH stimulates the remaining follicle cells to form the Corpus Luteum, Which Produces Both Estrogen And Progesterone. • • • Estrogen And Progesterone stimulate the development of the Endometrium and preparation of the uterine inner lining for implantation of a zygote. If pregnancy does not occur, the drop in FSH And LH Cause The Corpus Luteum To Disintegrate. The drop in hormones also causes the sloughing off of Functionalis Layer by a series of muscle contractions of the uterus Reproduction and the Menstrual Cycle 2 main phases: follicular and luteal phase – each 14 days Follicular phase (14 days) Includes menstrual flow phase (5 days) Hypothalamus triggers pituitary to secrete FSH Loss of 25-65 ml of blood average Causes the follicle to develop As follicle develops, starts to produce estrogen Estrogen has three important effects: Inhibits FSH production “we’ve got a follicle and don’t need to produce another one now” causes the endometrium lining to build up Causes the pituitary to secret LH LH surge causes ovulation: marks end of the follicular phase Reproduction and the Menstrual Cycle As FSH declines, causes the increase in secretion of LH (Luteinizing hormone). Spike in LH causes ovulation to occur After ovulation, in luteal phase After ovulation the follicle is called a corpus luteum Corpus luteum makes progesterone. Progesterone: inhibits pituitary manufacture of LH (and FSH) “We’ve got successful ovulation, don’t need anymore” LH surge (due to low FSH) triggers ovulation Estrogen (ovary) inhibits FSH production Follicle develops Corpus luteum makes progesterone, inhibits FSH, LH Reproduction and the Menstrual Cycle If pregnancy occurs… Estrogen and progesterone stay high FSH and LH stay low, the endometrium continues to grow Corpus luteum grows and dominates the ovary Most birth control pills contain the combination of the hormones estrogen and progesterone to prevent ovulation: inhibits FSH and LH