2/27/13Sexual DifferentiationPrenatal (in utero) development of the male and female reproductive structuresThe physical difference between male and female reproductive structuresGenetic sexEstablished at fertilizationXX femaleXY maleFinger LengthMost men’s ring finger is longer than index, the opposite is true for women…back to Sexual DifferentiationThe Y chromosome induces the indifferent gonads(neither male or female) to become testesThe testes produce hormones:Androgens: will act on the Wolffian duct system to induce internal male reproductive structures and on the external genitalia to induce male external structuresWollfian ducts respond to androgens to form seminal vesicles, vas deferens, and epididymisMale Sexual DifferentiationThe internal ejaculatory ducts lead toUrethraJunction of ducts of seminal vesiclesExternal genitalia in the male respond to a potent androgen called dihydrotestosterone to become male structures including:SrotumPenisProstate glandReceptors only respond to testosteroneFemale Sexual DifferentiationIf androgens are absent the Mullerian ducts will develop into internal female reproductive structures:OviductsUterusUpper portion of the vaginaThe external female structures develop into: (this occurs with no hormone involvement)ClitorisLabiaRest of the vaginaHomologous StructuresIt is clear that males and females are anatomically different, but the reproductive structures develop from the exact same tissuesIf androgens are present the tissues become male structures and w/o androgens they become the female structureSrotum --- Labia MajoraPenis --- ClitorisCowper’s glands --- Bartholin’s glandsTestes --- OvariesThey come from the same tissues and serve the same functionThe Critical Role of Y ChromosomesIt is the androgens from the developing testes that are criticalAndrenogenital SyndromeAffects both genders and roughly 1 in every 10,000 to 18,000 childrenCauses an excess of male sex hormone to be producedMale characteristics will formFor boys: has a YBasically an enhancement in pubertyFor girls: no YGenitalia could look like both gendersAmbiguous genitaliaTreatment for AGSFeminization of external genitaliaTreated with cortisone, hormones, and electrolytesSummary of AGSA female with AGS:OvariesOviductUterusVagineIs fertileHas some masculinization of external genitaliaAndrogen Insensitivity Syndrome2-5 out of 100,000 birthsAll individuals will have the genotype of XYThe cells of the body do not respond to androgensWolffian ducts are insensitive to male hormones so no male internal structures form except testes which remain in the abdomenNo female internal organsBut has the body build of a femaleExternal Structures of MalePenisErectile tissueCorpora cavernosa penisCorpus spongiosum penisUrethraScrotum3/4/14Male CircumcisionNumerous studies in Africa found that male circumcision (MC) significantly reduced the incidence of male HIV infectionNo protective effect of MC on females and HIV transmissionCircumcision lowers risk of STDSInternal Structures of MaleTestesLeydig cells: produce male hormones- -> androgensSeminiferous tubules: sperm productionBoth of these are under the control of the anterior pituitary hormonesEpididymis: sperm mature hereVas deferens: storage area for sperm cellsSeminal vesicles: thick mucus secretion essential for motility of sperm cellsEjaculatory ducts: lead to urethra and junction of ducts of seminal vesicles and vas deferensProstate gland: thin milky fluid helpful in sperm motility and buffers sperm cells while in female tractCowper’s gland: pre-ejaculatory emissionExternal Structures of FemaleCalled the vulvaLabia majoraLabia minoraForms protective hood over clitorisClitorisInternal Structures of FemaleVestibule of the vaginaUrethral orificeVaginal orifice3/6/13Bartholin’s glandsMons pubisOvaries: egg and hormone productionFallopian tubes: fimbriae cover surface of ovaryUterus:Perimetrium (outer layer)Myometrium (muscular layer)Endometrium (inner layer)Vagina: extends from vaginal orifice up to cervixReproductive PhsiologyEndocrinology:The study of ductless glands and their secretions called hormonesHormones are released directly into blood stream and have very specific targetsA gland with a duct would be a sweat gland with sweat released on skin surfaceNeuroendocrinology: the study of how the nervous system controls the endocrine systemHypothalamus: neurosecretory cells are located here and produce neurohormonesPosterior pituitary: attached to the hypothalamus via NERVE CELLS – stores neurohormones made in hypothalamusAnterior pituitary gland: attached to the hypothalamus via BLOOD VESSELS and make its OWN HORMONES and the release is controlled by neurohormones from hypothalamusNeurohormones from hypothalamus are called releasing hormones or releasing factorsGonadotropin hormone releasing hormone: (GnRH) is a releasing factor from hypothalamus that controls Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) from anterior pituitary glandGonadotropinsFSH and LH allow sperm and egg production to occurNegative Feedback SystemThe hypothalamus-anterior pituitary- gonadal system or axisTalk about ACSet point 67 degressFurnaceControllerComparatorSensorThe sensor senses the temp; comparator compares to set point, controller tells the furnace what to doNow biological systemHypothalamus GnRHAnterior PituitaryFSH LHOvariesIn a convent… ovaries stop functioningLevels of estrogen and progesterone dropHypothalamus boosts GnRH, which causes the anterior pituitary to pour out FSH and LH3/18/13Clicker Question: Frank is using Viagra. Will this influence testicular hormone levels?Answer: NoViagra just increases blood flow to the penisReproductive PhysiologyMale reproductive physiology compared to female reproductive systemMale is tonic (constant) vs. female which is cyclicMenstrual CycleMenarche: onset of first menstrual flowMenopause: the termination of mensesMenstruation: the monthly buildup and sloughing off of the endometriumLH and FSH peak in the middle of the cycleDay 1 is the day of the first flowEstrogen and progesterone peak before menstruationThe 1st half of the cycle is dominated by estrogenProgesterone predominates at the 2nd half of the cycle4 phases:1) menses: days 1 to 5low levels of all hormones2) estrogenic phase: days 6-13FSH and LH rise and estrogen rise3) ovulation: day 14estrogen levels peak, FSH and LH peaks and progesterone levels begin to risecount back 14 days from end of cycle…. Not
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