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Copyright © 2006 by Elsevier, Inc.
Male Reproductive System
Figure 80-1Guyton & Hall
Copyright © 2006 by Elsevier, Inc.
Cross section of the seminiferous tubule and stages of sperm
development
Figure 80-2Guyton & Hall
Copyright © 2006 by Elsevier, Inc.
hypothalamus
gonadotropin releasing hormone
ant. pituitaryLH FSH
Leydig cells Sertoli cells
androgens
growthfactors
inhibin
estrogens
androgenbindingprotein
spermatogenesis
aromatization
peripheralaromatization
Hypothalamic-pituitary-gonadal axis
(function 1)
(function 2)
pulsatile -- 8-14/24h
pulsatilepulsatile
_
_
_
+
_
Copyright © 2006 by Elsevier, Inc.
Copyright © 2006 by Elsevier, Inc.
Tissues Producing Androgens
cholesterol
androstenedione
testosterone
DHT E2
testisadrenal
peripheral tissues
5-reductase CYP 19
Copyright © 2006 by Elsevier, Inc.
Different Stages of Male Sexual Function:Plasma Testsosterone and Sperm Production
Figure 80-9; Guyton & Hall
Copyright © 2006 by Elsevier, Inc.
Cell Divisions DuringSpermatogenesis
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 ofprimary spermatocyte produces 4 maturespermatozoa
3. In female, second meiotic division is completedonly upon fertilization. In male, the products ofmeiosis (spermatids) undergo substantial differentiation in the maturing process.
Copyright © 2006 by Elsevier, Inc.
Figure 81-2; Guyton & Hall
Internal structures of the Uterus, Ovary and a Fallopian Tube.
Copyright © 2006 by Elsevier, Inc.
Fundamental reproductive unit = single ovarianfollicle, 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)ovulationluteal phase – 13-14 d – less variable than follicular
Endometrial cycle – menstruation, proliferative and secretory phases
Copyright © 2006 by Elsevier, Inc.
1 4 14 28
FSHLH
ovulationLHsurge
proliferative phase
(11 d)EndometrialCycle: menstrual
secretory phase (12d)
OvarianCycle: follicular phase
LH surge lasts 48 h
IncGnRHbursts
FSH and LH in the Follicular phase
Copyright © 2006 by Elsevier, Inc.
Copyright © 2006 by Elsevier, Inc.
1 4 14 28
FSH
LH
ovulationLHsurge
Proliferative phase(11 d)
EndometrialCycle: menstrual
Secretory phase (12d)
estradiolfeedback--GnRH
neg
OvarianCycle: 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.
Copyright © 2006 by Elsevier, Inc.
Figure 81-4;Guyton & Hall
Stages in follicular growth and ovulation.
Copyright © 2006 by Elsevier, Inc.Figure 81-7; Guyton & Hall
Phases of Endometrial Cycle
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 effectssuppress 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.
Copyright © 2006 by Elsevier, Inc.
Menopause
Defn: obsolescence of ovaries, no estradiol production, ovaonly 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%