Male Reproductive System Figure 80-1 Guyton & Hall Copyright © 2006 by Elsevier, Inc. Cross section of the seminiferous tubule and stages of sperm development Copyright © 2006 by Elsevier, Inc. Figure 80-2 Guyton & Hall _ _ Hypothalamic-pituitarygonadal axis hypothalamus gonadotropin releasing hormone _ pulsatile -- 8-14/24h _ ant. pituitary pulsatile FSH LH + Leydig cells growth factors Sertoli cells androgen binding protein spermatogenesis (function 2) estrogens Copyright © 2006 by Elsevier, Inc. inhibin aromatization androgens (function 1) peripheral aromatization pulsatile Tissues Producing Androgens cholesterol adrenal testis androstenedione testosterone 5-reductase DHT Copyright © 2006 by Elsevier, Inc. CYP 19 E2 peripheral tissues Different Stages of Male Sexual Function: Plasma Testsosterone and Sperm Production Figure 80-9; Guyton & Hall Copyright © 2006 by Elsevier, Inc. Cell Divisions During Spermatogenesis Figure 80-3; Guyton & Hall Copyright © 2006 by Elsevier, Inc. Differences between Spermatogenesis and Oogenesis 1. In females, mitotic proliferation of germ cells occurs prior to birth. In males, spermatogonia proliferate only after puberty. 2. In female, meiotic divisions of primary oocyte produces only one secondary oocyte. In male, meiotic divisions of primary spermatocyte produces 4 mature spermatozoa 3. In female, second meiotic division is completed only upon fertilization. In male, the products of meiosis (spermatids) undergo substantial differentiation in the maturing process. Copyright © 2006 by Elsevier, Inc. Internal structures of the Uterus, Ovary and a Fallopian Tube. Figure 81-2; Guyton & Hall Copyright © 2006 by Elsevier, Inc. Fundamental reproductive unit = single ovarian follicle, composed of one germ cell (oocyte), surrounded by endocrine cells Copyright © 2006 by Elsevier, Inc. 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 Copyright © 2006 by Elsevier, Inc. Ovarian Cycle: follicular phase ovulation FSH and LH in the Follicular phase LH surge LH surge lasts 48 h Inc GnRH bursts FSH LH 1 14 secretory phase (12d) 28 4 proliferative phase Endometrial (11 d) Cycle: menstrual Copyright © 2006 by Elsevier, Inc. Ovarian Cycle: follicular phase ovulation LH surge FSH estradiol LH neg feedback--GnRH 1 14 4 Proliferative phase Endometrial (11 d) Cycle: menstrual Copyright © 2006 by Elsevier, Inc. Increase in estradiol to stimulate LH surge. Then estradiol has Negative feedback on GnRH to reduce LH, FSH. Secretory phase (12d) 28 Stages in follicular growth and ovulation. Figure 81-4; Guyton & Hall Copyright © 2006 by Elsevier, Inc. Phases of Endometrial Cycle Figure 81-7; Guyton & Hall Copyright © 2006 by Elsevier, Inc. 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 Copyright © 2006 by Elsevier, Inc. 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. 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 Copyright © 2006 by Elsevier, Inc. Rat Data • Females – – – – – – – Average overall weight gain = 20.3% Average weight gain during HRT on E1 = 8.1% Average weight gain during HRT on E2 = 5.9% Average estrous cycle length = 4.2 days Vag smears with E1 = estrous phase Vag smears with E2 = diestrous phase • Males – – Average overall weight gain = 31.2% – Average weight gain during HRT on T1 = 8.2% – Average weight gain during HRT on T2 = 10.8% Copyright © 2006 by Elsevier, Inc.