Male Reproductive System Figure 80 1 Guyton Hall

Cross section of the seminiferous tubule and stages of sperm development Copyright © 2006

_ _ Hypothalamic-pituitarygonadal axis hypothalamus gonadotropin releasing hormone _ pulsatile LH Leydig cells _

Tissues Producing Androgens cholesterol adrenal testis androstenedione testosterone 5 -reductase DHT Copyright © 2006

Different Stages of Male Sexual Function: Plasma Testsosterone and Sperm Production Figure 80 -9;

Cell Divisions During Spermatogenesis Figure 80 -3; Guyton & Hall Copyright © 2006 by

Differences between Spermatogenesis and Oogenesis 1. In females, mitotic proliferation of germ cells occurs

Internal structures of the Uterus, Ovary and a Fallopian Tube. Figure 81 -2; Guyton

Fundamental reproductive unit = single ovarian follicle, composed of one germ cell (oocyte), surrounded

Menstrual cycle – controlled by gonadotropins, gonadal hormones Ovarian cycle – follicular phase –

Ovarian Cycle: follicular phase LH surge ovulation FSH and LH in the Follicular phase

Ovarian Cycle: follicular phase ovulation LH surge FSH estradiol LH neg feedback--Gn. RH 1

Stages in follicular growth and ovulation. Figure 81 -4; Guyton & Hall Copyright ©

Phases of Endometrial Cycle Figure 81 -7; Guyton & Hall Copyright © 2006 by

Contraception Rhythm method: if periodicity of menstrual cycle is 28 d, then ovulation should

Implant contraceptives: norprogestins: “Norplant” lasts 5 yrs Depoprovera – last 3 mos – inhibits

Menopause Defn: obsolescence of ovaries, no estradiol production, ova only occasional secondary follicle, few

Rat Data • Females – – – – Average overall weight gain = 20.

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_ _ Hypothalamic-pituitarygonadal axis hypothalamus gonadotropin releasing hormone _ pulsatile LH Leydig cells _ ant. pituitary + growth factors androgens (function 1) peripheral aromatization pulsatile -- 8 -14/24 h FSH pulsatile Sertoli cells aromatization androgen binding protein spermatogenesis (function 2) estrogens Copyright © 2006 by Elsevier, Inc. inhibin

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.

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 LH surge ovulation FSH and LH in the Follicular phase LH surge lasts 48 h Inc Gn. RH bursts FSH LH 1 14 secretory phase (12 d) 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--Gn. RH 1 14 4 Proliferative phase Endometrial (11 d) Cycle: menstrual Copyright © 2006 by Elsevier, Increase in estradiol to stimulate LH surge. Then estradiol has Negative feedback on Gn. RH to reduce LH, FSH. Secretory phase (12 d) 28

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 Gn. RH, 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 E 1 = 8. 1% Average weight gain during HRT on E 2 = 5. 9% Average estrous cycle length = 4. 2 days Vag smears with E 1 = estrous phase Vag smears with E 2 = diestrous phase • Males – – Average overall weight gain = 31. 2% – Average weight gain during HRT on T 1 = 8. 2% – Average weight gain during HRT on T 2 = 10. 8% Copyright © 2006 by Elsevier, Inc.