Anatomy & Physiology of the Female Reproductive Tract PDF

Anatomy & Physiology of the Female Reproductive Tract RIZVI, Fahad PHAS5001  ØDescribe the main anatomical features of the female reproductive tract ØRelate female anatomy to common clinical problems Learning ØD...

Anatomy & Physiology of the Female Reproductive Tract RIZVI, Fahad PHAS5001  ØDescribe the main anatomical features of the female reproductive tract ØRelate female anatomy to common clinical problems Learning ØDescribe the main physiological functions of Outcomes the female reproductive system, including: ØHormonal regulation ØOogenesis ØOvarian cycle  Bladder Urethra Uterus Ovary Vagina Rectum The thick wall of the uterus has 3 layers: 1. The endometrium is the inner layer that lines the uterus. It is made up of glandular cells that make secretions. 2. The myometrium is the middle and thickest layer of the uterus wall. It is made up mostly of smooth muscle. 3. The perimetrium is the outer serous layer of the uterus  Uterus Uterus is anteverted, i.e. anterior to vertical plane going through the vagina Pear-shaped muscular organ 8 cm long; 5 cm width; 3 cm thick Cervix opens into fornices of vagina Fundus is the portion above entrance of uterine tubes Covered with peritoneum  SF SB Uterine histology – the menstrual cycle Myometrium Menstrual corkscrew shaped glands SF SF Endometrium (SF+SB) spiral arteries SB Secretory SB Proliferative M M Ross and Pawlina; Histology, 5th Ed., LWW, 2006  Cervix Cervix Isthmus is a circular borderline area between the body and cervix Isthmus is the supra vaginal portion of cervix, the lower uterine segment Posterior is deeper covered with peritoneum Internal os is the opening from the cavity of body Spindle shaped cavity cervix External os is the opening into vagina  Vagina Thin walled tubes 8-10 cm which surround the cervix Normal anteverted and antiflexed Anterior fornix is shallow; anterior wall is shorter than posterior Posterior deeper, covered with peritoneum of the pouch of Douglas - lowest part of peritoneal cavity Walls normally in contact except superiorly Opens into vestibule of vagina  Ovary Hilum Blood vessels, nerves, lymphatics Marieb and Hoehn, 10th Ed. Ovarian Cortex – the site of oocyte development Contains ovarian follicles in various stages of development. Each follicle contains one oocyte. The appearance will vary with age and stage in the monthly cycle. From puberty to menopause every month a mature (Graafian) follicle expels a secondary oocyte by a process called ovulation.  Ovarian Cortex Histology TA GE Follicles (at different stages of development) Ross & Pawlina; Histology, 5th Ed. x120, H&E  Oogenesis The Ovaries: Undergoes monthly cycle in which an oocyte develops Formation of a secondary (2y) haploid (n) oocyte at ovulation which may or may not be fertilised. Similar to spermatogenesis; 1 x mitosis, 2 x meiosis Each embryonic ovary contains ~1000-2000 primordial germ cells that divide by mitosis to form around 3 million oogonia. Sequence includes mitosis (in utero), meiosis I (after puberty each month) and meiosis II (at fertilisation). Oocytes develop in ‘follicles’ with a visible sequence of follicular changes. Defined by the Follicular phase and Luteal Phase  Oogonium Stem cell 2n 1y oocytes are made in utero Mitosis 2 Ch, 2 Ctd 1y oocyte (identical) 2n 2n STOPS AT PROPHASE 1 of Meiosis 1 Meiosis 1 Ovulation each month post-puberty 2y oocyte Pb n 1y Oocyte GOES FROM P1 AND STOPS AT M2 AS A 2y Oocyte. 1 Ch, 2 Ctd Meiosis 2 In fallopian tube 1 Ch, 2 Ctd pb n 1 Ch, 1 Ctd 1y – primary 1 Ch, 1 Ctd pb 2y – secondary ovum M2 COMPLETES IF 2n – diploid 2y OOCYTE IS FERTILISED n – haploid Pb – polar body (these disintegrate) n  FOLLICLE DEVELOPMENT Oogonium 2n Stem cell Mitosis In utero 2n 2n 1y oocyte 2n Primordial follicle Meiosis 1 Puberty to menopause each month Meiosis 1 2n 1y follicle 2n 2y follicle Graafian follicle 2y oocyte n ovulation  Oocytes develop in follicles Primary Secondary Mature Graafian *Not to scale – Primary much smaller than Graafian  Oocytes develop in Follicles Follicular Stages: Primordial Primary Secondary Follicular phase Antral Corpus luteum Corpus albicans Luteal phase Marieb and Hoehn, 10th Ed.  Key features to remember Primordial - 1y oocyte, follicular cells Primary – 1y occtye, zona pellucida, theca interna & externa, granulosa cells Secondary (early antral/vesicular*) – 1y oocyte Graffian (vesicular*) – 2y oocyte, antrum, follicular fluid, corona radiata, cumulus oophorius, Ovulation Corpus luteum – endocrine secretion of progesterone Corpus albicans – degenerating corpus luteum *Note: Marieb’s uses slightly odd follicle gradings. I’d like you to use the terminology here which is more widely used. Ovulation The rupture of the Graafian follicle and release of 2y oocyte into the pelvic cavity Usually just one oocyte Occurs around day 14 of the 28-day cycle caused by hormonal changes leading to a LH surge. A combination of hormonal changes and enzymatic effects Increased volume and pressure of follicular fluid Enzymatic proteolysis of follicular wall Theca interna contraction 2y The remaining follicle forms the corpus luteum pb Endocrine Regulation of Ovarian Function Ovaries are responsible for oogenesis and cyclic (~28 days) synthesis of steroidal oestrogens and progesterone. Principal events of menstrual cycle in the uterus can be correlated with those of the ovarian cycle and changes in the endometrium - all are hormonally controlled events. Ovarian Cycle Monthly series of events associated with the maturation of an ovum Hypothalamus Synthesis and secretion of oestrogens from theca / granulosa cells GnRH Synthesis and secretion of progesterone from the corpus luteum Ant. Pituitary Gonadotrophs Regulated by anterior pituitary gonadotrophins, LH and FSH (FSH) LH Oestrogen/ Gonad Testosterone Progesterone Follicle Stimulating Hormone (FSH): Stimulates growth of granulosa cells and initial development of primary ovarian follicles Stimulates synthesis and secretion of oestrogens and inhibin from granulosa cells (-ve feedback) Up-regulates LH receptors in granulosa cells Many follicles may begin to mature during each cycle but only one dominant follicle will mature to a secondary follicle Luteinising Hormone (LH): The dominant follicle that will ovulate is that which most rapidly acquires LH receptors Thereby most rapidly reacts to raising LH concs. LH stimulates later development of ovarian follicles A surge of LH induces ovulation - peak at day 13-14 Stimulates production of oestrogens via theca cells Stimulate production of progesterone by CL Anti Mullerian Hormone Produced by granulosa cells. Prevents development of surrounding primary follicles. Tortora: Principles of human anatomy and physiology. 11th Edition  The Ovarian Cycle +ve Feedback Tortora: Principles of human anatomy and physiology. 11th Edition Feedback Tortora: Principles of human anatomy and physiology. Principles of Human Anatomy 25 11th Edition and Physiology, 11e  The Menstrual Cycle Series of changes in the endometrium of the non-pregnant female Regulated by ovarian steroids Each month endometrium (Strat. basalis and Strat. functionalis) prepared to nourish and receive a fertilized ovum If no fertilization occurs, the stratum functionalis is shed (menstruation) Three histologically distinct stages in women that relate to affects of ovarian steroid Ovarian steroids regulate the cycle 1st Menstrual Stage: shedding of stratum functionalis if CL progesterone is lost Proliferative 2nd Stage: Ovarian oestrogens promote proliferation and repair of Strat. Functionalis. Secretory 3rd Stage: Oestrogen and progesterone from the CL promotes uterine receptivity and glandular secretions. If hCG from the placenta does not take over the role of LH then the CL atrophies Tortora: Principles of human anatomy and physiology. 11th Edition Menopause Menopause Peak of reproductive ability is in 20s By mid 40s most women are not able to conceive naturally % of follicles Ovaries become less response to gonadotropin signals Oestrogen production declines Once ovulations ceases this is called the menopause Age (years) Average age ~ 50  Menopause Lack of oestrogen leads to many side effects, including: Vagina becomes dry Hot flushes Decreased libido Difficulty sleeping Mood changes, anxiety & depression Palpitations Higher risk of UTIs Treatment: Hormone Replacement Therapy if required Clinical problems Dysmenorrhoea Amenorrhoea Endometriosis PCOS Amenorrhoea Strenuous physical activity can delay menarche or disrupt normal menstrual cycle Female athletes have very low % body fat Adipose tissues are the source of leptin Leptin stimulates release of GnRH Usually reversible once training stops