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HUMAN REP R O D UCTI O N

HUMAN REP R O D UCTI O N. TH E MAL E R E P R ODUCTIV E S Y S TE M. Loc a ted in the pel v is r e g ion. Male r ep r o d u c ti v e syst e m incl u des A p air o f testes. Accesso r y d u cts. Accesso r y glan d s. Exte r n a l genita l ia. T e s t es:.

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HUMAN REP R O D UCTI O N

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  1. HUMANREPRODUCTION

  2. THEMALEREPRODUCTIVESYSTEM. • Locatedinthepelvisregion. • Malereproductivesystemincludes • Apairoftestes. • Accessoryducts. • Accessoryglands. • Externalgenitalia

  3. Testes: • Locatedoutsidetheabdominalcavitywithinapouchcalledscrotum. • Scrotumprovideslowtemperaturerequiredforspermatogenesis. • Eachtestisisabout4to5cmlengthand2to3cmwidth. • Eachtestishasabout250compartmentscalledtesticularlobules. • Eachlobulecontainsonetothreeseminiferoustubules. • SeminiferoustubuleslinedbymalegermcellsandSertolicells. • Malegermcellundergoesmeiosisandproducesperm. • Sertolicellsprovidenutritiontothegermcellandthesperm. • InbetweentheseminiferoustubulethereisinterstitialcellorLeydigcell. • Leydigcellsproducetesticularhormones • calledandrogen(testosterone).

  4. Accessoryducts: • Includesretetestis,vasaefferentia,epididymisandvasdeferens. • Seminiferoustubulesopenintovasaefferentiathroughrete • testis. • Thevasaefferentialeavesthetestisandopenintoepididymis. • Theepididymisleadstovasdeferensthatascendstotheabdomenthroughinguinalcanalandloopsovertheurinarybladder. • Vasdeferensreceivesaductfromseminalvesicleandopensintotheurethraastheejaculatoryduct. • Urethraoriginatesfromtheurinarybladderandextendsthroughthepenistoitsexternalopeningcalledurethralmeatus.

  5. Accessoryglands: • Includes • Pairedseminalvesicle • Aprostategland • Pairedbulbourethralgland. • Secretionoftheseglandsconstitutestheseminal • plasma. • Seminalplasmarichinfructose,calcium,andcertainenzyme. • Secretionofbulbo-urethralglandshelpsin • lubricationofpenis.

  6. Externalgenitalia: • Penisistheexternalgenitalia. • Itismadeofspecialtissuethathelpsinerectionofthepenistofacilitateinsemination. • Theenlargedendofpenisiscalledglanspenis. • Glanspenisiscoveredbyaloosefoldofskin • calledforeskin.

  7. THEFEMALEREPRODUCTIVESYSTEM • Locatedinthepelvicregionofthefemale. • Thefemalereproductivesystemincludes: • Apairofovaries • Apairofoviduct. • Uterus • Cervix • Vagina • Externalgenitalia. • Apairofmammary • gland

  8. Ovaries: • Itistheprimaryfemalesexorgansthatproducethefemalegamete(ovum). • Italsoproducesseveralsteroidhormones. • Theovarieslocatedinthelowerabdomen. • Eachovaryisabout2-4cminlength. • Connectedtothepelvicwallanduterusbyligaments. • Eachovaryiscoveredbythinepitheliumwhichenclosestheovarianstroma • Theovarianstromahastwozones • Aperipheralcortex. • Aninnermedulla.

  9. Oviduct: • Oviducts,uterusandvaginaconstitutethefemaleaccessoryducts. • Eachfallopiantubeisabout10-12cmlongandextendsfromthe • peripheryofeachovarytotheuterus. • Closetotheovarytheoviducthasafunnelshapedstructurecalledinfundibulum? • Theedgesoftheinfundibulumpossessfinger-likeprojectionscalledfimbriae,whichhelpsincollectionoftheovumafterovulation. • Theinfundibulumleadstoawiderpartoftheoviductcalledampulla. • Thelastpartoftheoviductiscalledisthmuswhichjoinedtouterus.

  10. Uterus: • Itissingleandiscalledwomb. • Itisinvertedpearshaped. • Attachedthepelvicwallbyligaments. • Theuterusopensintovaginathroughanarrowcervix. • Thelumenofcervixiscalledcervicalcanal. • Cervicalcanalalongwithvaginaformthebirthcanal. • Thewalloftheuterushasthreelayersoftissues • Perimetrium:externalthinmembranous. • Myometrium:middlethicklayerofsmoothmuscles • Endometrium:innerglandularlayer. • Endometriumundergoescyclicalchangesduringmenstrualcycle. • Myometriumexhibitsstrongcontractionduringdeliveryofthebaby.

  11. Externalgenitalia: • Itincludesfollowingstructure: • MonsPubis:cushionoffattycovered • byskinandpubichair. • Labiamajora:fleshyfoldsoftissuewhichextendsdownfromthemonspubisandsurroundsthevaginalopening. • Labiaminora:arepairedfoldsof • tissueunderthelabiamajora. • Hymen:theopeningofvaginaisoftencoveredpartiallybyamembranecalledhymen. • Clitoris:atinyfinger-likestructureliesattheupperjunctionoftwolabiaminoraabovetheurethralopening.

  12. Mammaryglands: • Mammaryglandconsistsofglandulartissueandfat. • Glandulartissueofeachbreastdividedinto15-20mammarylobes. • Mammarylobescontainclusterofcellscalledalveoli. • Thecellsofalveolisecretemilk,storedinthelumenofalveoli. • Thealveoliopenintomammarytubules. • Thetubulesofeachlobejointoformamammaryduct. • Severalmammaryductsjointoformawidermammaryampulla. • Mammaryampullaconnected • tolactiferousduct,throughwhichmilkissuckedout.

  13. GAMETOGENESIS:(formationofgametes) • Spermatogenesis: • Formationofspermfromthegermcellinthetestesisspermatogenesis. • Theprocessbeginsatpuberty. • Spermatogoniapresentintheliningofseminiferoustubulesundergomitoticdivisiontoincreasetheirnumber. • Eachspermatogoniumisdiploid(2n)whichcontain46chromosomes. • Innermostlayerofspermatogonialbecomeslargercalledprimaryspermatocyte. • Primaryspermatocyteundergoesmeiosis-Itoformtwoequalhaploid(n)secondary • spermatocytes(n). • Eachsecondaryspermatocyteundergoesmeiosis-IItoformtwoequal,haploidspermatids. • Eachprimaryspermatocyteproducesfourspermatids. • Spermatidstransformedintospermatozoa(sperms)bytheprocesscalledspermiogenesis. • ThespermheadembeddedintheSertolicell. • Releaseofspermfromtheseminiferoustubuleiscalledspermiation.

  14. SPERMATOGENESISPROCESS

  15. Hormonalcontrolofspermatogenesis: • Thisprocessisinitiatedatpubertyduetosecretionofgonadotrophinsreleasinghormone(GnRH) • GnRHsecretedformhypothalamusandstimulateanterior • pituitarytosecretetwogonadotrophins. • Luteinizinghormone(LH)and • FolliclestimulatingHormone(FSH) • LHactsonLeydigcellsandstimulatessynthesisof • androgens. • Androgenstimulatesspermatogenesis. • FSHactsonSertolicellsandstimulatesspermatogenesisinotherways.

  16. Structureofsperm: • Ultrastructureofspermconsistsofahead,neck,amiddlepieceandatail. • Wholebodyofspermsurroundedbyplasmamembrane. • Thespermheadcontainanelongatedhaploidnucleus. • Abovethenucleusacaplikestructurepresentcalledacrosome. • Theacrosomecontainsenzymeswhichhelpinfertilizationofovum. • Themiddlepiececontainsmitochondria,whichprovideenergyformovementoftailthatfacilitatespermmotility. • Humanmaleejaculates200-300millionspermsduringcoitus. • 60percentmusthavenormalshapeandsizeand40percentofthemmustshow • vigorousmotility. • Spermreleasedfromseminiferoustubulesentersintoaccessoryducts. • Ontheirwayfluidsfromseminalvesicleandprostateglandaddedwhich • collectivelycalledasSemen. • Thefunctionofmaleaccessoryductsandglandsaremaintainedbytesticularhormoneandrogen.

  17. SPERMSTRUCTURE

  18. Oogenesis: • Formationofamaturefemalegameteorovumiscalledoogenesis. • Oogenesisstartsduringembryonicstage,25thweekofthefetalage. • Germinalepitheliumofovarydividedmitoticallytoproducemillionsofgametemothercelloroogonia. • Nooogoniaformedoraddedafterbirth. • Oogoniaentersintomeiosis-IandproceedsuptodiakinesisofProphase-Iandgetsuspended,atthisstagecalledprimaryOocytes. • Eachprimaryoocytesurroundedbylayersofgranulosecellsandthencalledprimaryfollicle. • Atpubertyonly60,000to80,000primaryoocytesareleftineachovary. • Afterpubertyprimaryfolliclesgetsurroundedbymorelayersofgranulosacellsand • anewthecatoformsecondaryfollicles. • Thesecondaryfollicletransformedintotertiaryfollicle,characterizedbyafluidfilledcavitycalledantrum. • Thethecalayersorganizedintoaninnerthecainternaandouterthecaexterna. • Duringthegrowthofprimaryfollicleintotertiaryfollicleduringpuberty,theprimaryoocyterestartsitsfirstmeioticdivisionandcompletesitwithintertiaryfollicleresultingtwounequalhaploidcells. • Largehaploidcelliscalledsecondaryoocyte. • Atinycellcalledfirstpolarbody.

  19. CONT…. • Thesecondaryoocyteretainsbulkofthenutrientrichcytoplasmofprimaryoocyte. • Thetertiaryfolliclehavingsecondaryoocyte • furtherchangesintoGraafianfollicle. • Thesecondaryoocytesurroundedbyanewmembrane,zonapellucida. • Thesecondaryoocyteundergoessecondmeioticdivisioncontinueduptometaphase-IIandgetsuspendeduntilentryofsperm. • AtthisstageGraafianfolliclereleasessecondaryoocytefromtheovarybytheprocesscalledovulation. • Onentryofaspermintothesecondaryoocytesstimulatesittocompletemeiosis-IIandthereisformationofahaploidovumandasecondpolarbody(n).

  20. Menstrualcycle: • Reproductivecycleoffemaleprimatesiscalledmenstrualcycle. • ThefirstmenstruationbeginsatpubertyiscalledMenarche. • Menstrualcyclerepeatedatanaverageintervalof • 28/29days. • Oneovumisreleasedinthemiddleofeachmenstrualcycle.

  21. Menstrualcyclehasfollowingphases: • Menstrualphase: • 1stphaseofmenstrualcycle. • Menstrualflowoccurs. • Lastsfor3-5days. • Breakdownofendometrialliningandbloodvessel. • Mucusandbloodcomesoutthroughvagina. • Itoccursonlywhenovumreleasedbutnofertilization. • Lackofmenstruationistheindicationofpregnancy.

  22. Follicularphase: • Menstrualphasefollowedbyfollicularphase. • PrimaryfolliclebecomesGraafianfollicle. • Regenerationandproliferationofuterineendometrium. • LHandFSHlevelincreasesgraduallyinfollicular • phase. • Levelofestrogenincreasesasitissecretedfromgrowingfollicle. • Itlastsfor5-13days.

  23. Ovulatoryphase: • FSHandLHattainpeaklevelinthisperiod(14thday). • ThisiscalledLHsurge,whichinducesruptureofGraafianfollicleandreleaseofovumfromtheovarycalledovulation.

  24. Lutealphase: • RemainingpartofGraafianfollicletransformedintocorpusluteum. • Coupusluteumproduceslargeamountofprogesterone. • Progesteronemaintainstheuterineendometrium,andpreparesitforimplantation. • Thicknessofuterineendometriumincreaseinmanyfolds,duetoproliferation. • Ifthereisfertilization,corpusluteumgrowsfurtherand • pregnancycontinued,menstrualcyclestopped. • Intheabsenceoffertilizationcorpusluteumdegenerates. • Disintegrationofendometriumleadingtomenstruation. • Menstrualcycleceasesaround50yearsofage, • calledmenopause.

  25. FERTILIZATIONANDIMPLANTATION: • Duringcopulation(coitus)semenisreleasedbythepenisintothevaginaiscalledinsemination. • Themotilespermswimrapidly,passthroughcervix,uterusandfinallyreachthejunctionofisthmusandampulla(ammpullary-isthmicjunction). • Theovumreleasedfromtheovaryalsotransportedtoampullaryisthmicjunctionwherefertilizationtakesplace. • Fertilizationonlytakesplaceifbothspermandovumreachampullary– isthmicjunctionsimultaneously. • Theprocessoffusionofaspermandovumiscalledfertilization. • Acrosomeofspermsecretesenzymeshelpsin • penetrationintotheovum.

  26. CONT… • Onceaspermcomescontactwiththezonapellucidaofovumandinducesthechangesinthemembranethatblockstheentryofadditionalsperms. • Thatensuresmonospermyandpreventspolyspermy. • Onlyonespermfertilizewithoneovum. • Entryofspermintotheovuminducestheovumtocompleteitssecondmeioticdivisionofsecondaryoocyte. • Meiosis-IIisalsounequalcytokinesisresultingproductionofonelargeovum(ootid)andonesmallsecondpolarbody. • Haploidnucleusofspermfusedwiththehaploid • nucleusofovumtoformadiploidzygote.

  27. Thezygoteundergoesaseriesofmitoticcelldivisionscalledcleavage.Thezygoteundergoesaseriesofmitoticcelldivisionscalledcleavage. • Thestagesofdevelopmentare: Fertilizedovum(zygote) 2-cellstage 4-cellstage 8-cellstage Morula Blastula Gastrula

  28. Sexdetermination: • Sexofababyhasbeendecidedduringfertilizationandinthezygote. • Sexisdeterminedbythesex-chromosomespresentin • gametes. • HumanfemalecontaintwoXXchromosomes. • HumanmalecontainXYchromosomes. • All the female gametes produced with only ǮXǯ chromosome. • Sperms produced by male, 50% with ǮXǯ and 50 % with ǮYǯ • chromosome. • AfterfertilizationzygoteeithercarriesXXorXYchromosomes. • ZygotewithXXchromosomesdevelopintofemaleandwith • XYchromosomedevelopsintomale

  29. Cleavage: • Repeatedmitoticdivisionofthezygotewithoutgrowthresultingamulticellularballlikeembryoiscalledcleavage. • Cleavagestartssoonafterfertilization. • Daughtercellsproducedduringcleavagearecalledblastomeres. • TheproductofcleavageiscalledMorula,whichis8to16celled. • Themorulacontinuestodivideandgrowandtransformedintoblastocyst. • Theblastomeresinblastocystarrangedintoanouterlayer • calledtrophoblastandaninnermassofcellsattachedtotrophoblast • calledinnercellmass. • Trophoblastcellsattachedtotheendometriumhelpsdevelopmentofplacenta. • Innercellmassgetsdifferentiatedintotheembryo. • Afterattachmenttheuterinecellsdividerapidlyandcoverthe • blastocyst. • Blastocystcompletelyembeddedintheuterineendometrium.Thisiscalledimplantation.

  30. Pregnancyandembryonicdevelopment: • Afterimplantation,fingerlikeprojectionsappearsonthetrophoblastcalledchorionicvilli. • Chorionicvillisurroundedbyuterinetissueandmaternalblood. • Temporaryassociationbetweenthefetaltissue(chorionicvilli)andmaternaltissue(uterineendometrium)iscalledplacenta.

  31. Functionofplacenta: • Theembryoconnectedtotheplacentabyumbilicalcord,whichtransportssubstancestoandfromtheembryo. • Facilitatetransportofoxygenandnutrientfrommothertoembryo. • RemovesCO2andwastematerialfromtheembryo. • Actsasendocrineglandandproducesseveralhormones • like: • Humanchorionicgonadotrophins(hCG) • Humanplacentallactogen(hPL) • Estrogen. • Progesterone • Relaxinproducedfromtheovaryinthelaterstageof • pregnancy.

  32. Embryonicdevelopment: • Afterimplantationtheinnercellmassofblastocystdifferentiatedintoanouterlayercalledectodermandaninnerlayercalledendoderm. • Mesodermdifferentiatedin-betweenectodermandendoderm. • Theinnercellmassthuscalledstemcells,havingpotencytoproducealltypesofcell,tissuesandorgansbydifferentiation.

  33. Organogenesis: • Formationofdifferentorgansintheembryoiscalledorganogenesis. • Humanpregnancylastsfor9months. • Afteronemonthofpregnancyheartisformedintheembryo. • Bytheendof2ndmonththefoetusdevelopslimbsanddigits. • Bytheendof12weeks(firsttrimester)mostoforgansystemisformed(limbsandexternalgenitaliaarewelldeveloped). • Firstmovementoffoetusandappearanceofhairsobservedin5thmonth. • Bytheendof24thweek(2ndtrimesters)thebodyiscoveredwithfinehairs,eye-lidsseparate,andeyelashesareformed. • Bytheendof9monthsthefoetusisfullydevelopedandisreadyfordelivery.

  34. PARTURATIONANDLACTATION: • Theperiodofpregnancyiscalledgestationperiod.(9months). • Ejectionorexpulsionordeliveryoffoetusiscalledparturition. • Parturitionisduetovigorouscontractionofuterine • Myometrium. • Thesignalofparturitionisoriginatedfromthefullydevelopedfoetusandtheplacentawhichinducesmildcontractionofuteruscalledfetalejectionreflex. • FetalejectionreflextriggersthereleaseofOxytocinfrompituitary. • Oxytocininducesstrongercontractionofuterineendometrium. • Stimulatoryreflexcontinuesstrongercontractionleadstoexpulsion. • Afterdeliverytheplacentaisalsoexpelledoutoftheuterus.

  35. Lactation: • Themammaryglandofthefemalemoredifferentiatedduringpregnancy, • Mammaryglandstartsproducingmilktowardstheendof • thepregnancy. • Processofmilkproductioninmammaryglandis • calledlactation. • Milkproducedduringinitialdaysoflactationiscalledcolostrum. • Colostrumcontainsseveralantibodieswhichprovideimmunitytothenewbornbaby.

  36. Thankingyou

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