Reproductive Endocrinology - Guyton Ch. 80, 81 (Powerpoint)

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Reproductive Endocrinology - Guyton Ch. 80, 81 (Powerpoint)

  1. 1. Male Reproductive System Figure 80-1 Guyton & Hall
  2. 2. Cross section of the seminiferous tubule and stages of sperm development Figure 80-2 Guyton & Hall
  3. 3. hypothalamus gonadotropin releasing hormone ant. pituitary LH FSH Leydig cells Sertoli cells androgens growth factors inhibin estrogens androgen binding protein spermatogenesis aromatization peripheral aromatization Hypothalamic-pituitary- gonadal axis (function 1) (function 2) pulsatile -- 8-14/24h pulsatile pulsatile _ _ _ + _ Copyright © 2006 by Elsevier, Inc.
  4. 4. Tissues Producing Androgens cholesterol androstenedione testosterone DHT E2 testis adrenal peripheral tissues 5  -reductase CYP 19
  5. 5. Different Stages of Male Sexual Function: Plasma Testsosterone and Sperm Production Figure 80-9; Guyton & Hall
  6. 6. Cell Divisions During Spermatogenesis Figure 80-3; Guyton & Hall
  7. 7. Differences between Spermatogenesis and Oogenesis <ul><li>In females, mitotic proliferation of germ cells occurs </li></ul><ul><li>prior to birth. In males, spermatogonia proliferate </li></ul><ul><li>only after puberty. </li></ul><ul><li>In female, meiotic divisions of primary oocyte produces </li></ul><ul><li>only one secondary oocyte. In male, meiotic divisions of </li></ul><ul><li>primary spermatocyte produces 4 mature </li></ul><ul><li>spermatozoa </li></ul><ul><li>In female, second meiotic division is completed </li></ul><ul><li>only upon fertilization. In male, the products of </li></ul><ul><li>meiosis (spermatids) undergo substantial </li></ul><ul><li>differentiation in the maturing process. </li></ul>
  8. 8. Figure 81-2; Guyton & Hall Internal structures of the Uterus, Ovary and a Fallopian Tube.
  9. 9. Fundamental reproductive unit = single ovarian follicle, composed of one germ cell (oocyte), surrounded by endocrine cells
  10. 10. Menstrual cycle – controlled by gonadotropins, gonadal hormones Ovarian cycle – follicular phase – avg 15 d (range, 9-23 days) ovulation luteal phase – 13-14 d – less variable than follicular Endometrial cycle – menstruation, proliferative and secretory phases
  11. 11. 1 4 14 28 FSH LH ovulation LH surge proliferative phase (11 d) Endometrial Cycle: menstrual secretory phase (12d) Ovarian Cycle : follicular phase LH surge lasts 48 h Inc GnRH bursts FSH and LH in the Follicular phase Copyright © 2006 by Elsevier, Inc.
  12. 12. 1 4 14 28 FSH LH ovulation LH surge Proliferative phase (11 d) Endometrial Cycle: menstrual Secretory phase (12d) estradiol feedback--GnRH neg Ovarian Cycle: follicular phase Increase in estradiol to stimulate LH surge. Then estradiol has Negative feedback on GnRH to reduce LH, FSH. Copyright © 2006 by Elsevier, Inc.
  13. 13. Figure 81-4; Guyton & Hall Stages in follicular growth and ovulation.
  14. 14. Figure 81-7; Guyton & Hall Phases of Endometrial Cycle
  15. 15. Contraception Rhythm method : if periodicity of menstrual cycle is 28 d, then ovulation should be day 13-15: temp decreases and then increases slightly following ovulation. Also, consistency of mucus discharge from the vagina changes. Now, ovulation kits available. Oral, patch contraceptives: ethinyl estradiol, mestranol; gestodene, norgestimate – decr. androgenic effects suppress GnRH, FSH, LH – prevent LH surge (no ovulation) progestins: cervical mucus thickens, inhibit motility – decr. transport of ova and sperm – endometrium not conducive to implantation
  16. 16. Implant contraceptives: norprogestins: “Norplant” lasts 5 yrs Depoprovera – last 3 mos – inhibits ovulation, implantation Intrauterine device – IUD – spermicidal effect caused by sterile inflammatory reaction – secondarily prevents implantation of zygote Barrier methods: diaphragm with spermicidal jelly, condoms Postcoital contraceptives: RU 486 – not approved for use “ Plan B” – oral contraceptives used within 72 hrs of unprotected intercourse Tubal ligation Vasectomy Copyright © 2006 by Elsevier, Inc.
  17. 17. Menopause Defn: obsolescence of ovaries, no estradiol production, ova only occasional secondary follicle, few primary follicles Occurs at 51.4 yr of age (average) Due to reduction in estrogen, low levels of inhibin, no negative feedback of LH and FSH; therefore, high levels LH and FSH Can occur naturally, due to surgery or as a result of chemotherapy
  18. 18. Rat Data <ul><li>Females – </li></ul><ul><ul><li>Average overall weight gain = 20.3% </li></ul></ul><ul><ul><li>Average weight gain during HRT on E1 = 8.1% </li></ul></ul><ul><ul><li>Average weight gain during HRT on E2 = 5.9% </li></ul></ul><ul><ul><li>Average estrous cycle length = 4.2 days </li></ul></ul><ul><ul><li>Vag smears with E1 = estrous phase </li></ul></ul><ul><ul><li>Vag smears with E2 = diestrous phase </li></ul></ul><ul><li>Males – </li></ul><ul><ul><li>Average overall weight gain = 31.2% </li></ul></ul><ul><ul><li>Average weight gain during HRT on T1 = 8.2% </li></ul></ul><ul><ul><li>Average weight gain during HRT on T2 = 10.8% </li></ul></ul>

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