Reproductive System for Bsc Nursing students

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1 REPRODUCTIVESYSTEM
Reproductiveisthejointactionofmaleandfemalereproductivesystem.
Eachsystemproducesagametewhichcarriesthegeneticmaterialofthe
individual.Alongwiththis,thefemalereproductivesystemhastheadditional
responsibilityofmaintainingtheembryowithinit.Femalesareequippedto
nourishthenewbornbabiesbylactation.Themalegameteiscalled
spermatozoaandthefemalegameteiscalledovum.Thespermatozoaandthe
ovafusedtogethertoformthezygoteandthatbeginstheprocessof
developmentofnewindividual.
SEXDIFFERENTIATION
Whetherthezygotewilldevelopintoamaleorafemaleisdeterminedbythe
presenceorabsenceoftheYchromosomeinit.IftheYchromosomeispresent,
thezygotedevelopsintoamale,ifnotitbecomesafemale.ThepresenceofY
chromosomeleadstodevelopmentoftestesandsubsequentmalecharacters.
AbsenceofYchromosomeleadstodevelopmentofafemaleautomatically.
DEVELOPMENTOFREPRODUCTIVESYSTEM:
Intheembryo,atthestart(6
th
week)thereproductivesystemisbi-
potentialthatiseitherdevelopintoamaleorafemale.Thisiscomposedofthe
primitivegonadscontainingacortexandmedulla,theMullerianductsystemand
theWolffianductsystem.Theexternalgenitaliaarealsobi-potentialupto
eighthweek.IntheshortarmofY–chromosomeisthesexdetermininggene
(SRYgene)whichcordforthetestisdeterminingfactor(TDF).TheTDFis
responsibleforthedevelopmentoftestisfromthemedullaoftheprimitive
gonads.ThetestisnowdevelopedsecretestestosteronefromtheLeydiccells
undertheinfluenceofHCGandMullerianinhibitingfactor(MIF)fromthesertoli
cells.MIFcausesregressionofthemulleriansystemandthetestosterone
leadstodevelopmentofWolffiansystemintoepididymisandvasdeferns.
Testosteroneisalsoresponsibleforthedevelopmentofmaleexternalgenitalia.
WhenYchromosomeisabsentthereisnoformationofTDFandthe
cortexoftheprimitivegonadsdevelopsintoovariesautomatically.The

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1 embryonicovariesneednotsecreteandtheMulleriansystemdevelopsinto
Uterusanduterinetubes.Thefemalegenitaliaalsodevelopfromtheprimitive
genitaliaautomatically.
PUBERTY
Theperiodoflife,whentheendocrineandgametogenicfunctionofthe
gonadshavedevelopedforthefirsttimetothepointwherereproductionis
possible,iscalledpuberty.Thesechangesleadingtoadulthoodoccurs
graduallythroughaperiodoflifeandthisperiodiscalledadolescents.Ageof
onsetofpubertyinfemale:12–15yrsand.inmale11–14yrs.
PubertychangesinFemales
1.Breastdevelopmentstarts.Itisthefirstsignofadolescentsandis
calledThelarche.
2.Growingofaxillaryandpubichairs.
3.Initiationofmenstruation:thefirstmenstruationiscalled
Menarchae.
4.Duetothedepositionoffatinbuttocks,thighsandbreasts,anditgive
afemininelooks.
5.Voicebecomehighpitched.
6.Femaletypeofdistributionofbodyhairs.
7.Enlargementandwideningofpelvis
8.Enlargementofuterusandvaginaetc.,
9.Thereissuddenspurtofgrowth
10.Attractiontowardsoppositesex.
PubertychangesinMales
1.Voicebecomedeeperduetogrowthoflarynxandchangesinvocal
cord
2.Seminalvesicle,prostateandbulbourethralglandgrowandstart
secreting
3.Thepenisincreaseinsize,thereisgrowthoftestisandscrotumwith
pigmentationandpuckeringofscrotalskin

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1 4.Thereisatemporalrecessionofhairline,appearanceofbeard,pubic
hair,axillaryhairandhairsonthechest.
5.Shoulderisbroadenedandpelvisremainsnarrow,thereisincreasingin
musclemass.
6.Duetoincreasesebaceoussecretion,facebecomeoilyandacnemay
develop.
7.Developedattractiontowardsoppositesex.
MALEREPRODUCTIVESYSTEM
FUNCTIONSOFTESTIS
1.Gametogenicfunctions:Itisageneraltermthatreferstotheproductionof
gametesinthegonads
2.Endocrinefunction:Secretionofmalesexhormone.

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1 SPERMATOGENESIS
Itistheprocessbywhichthemalegametescalledspermatozoaare
formedfromtheprimitivegermcellsinthetestis.Ittakes74daysforthe
formationofspermfromprimitivegermcells.Throughouttheprocessof
spermatogenesis,thegermcellshavecytoplasmicattachmentwithsertolicells.
Sertolicellssupplyallthenecessarymaterialsforspermatogenesisthroughthe
cytoplasmicattachment.
STAGESOFSPERMATOGENESIS
1.Stageofproliferation
2.Stageofgrowth
3.Stageofmaturation
4.StageofTransformation
5.
1.StageofProliferation:Eachspermatogoniumcontainsdiploidnumberof
chromosome.Duringtheproliferativestage,spermatogoniadividebymitosis

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1 withoutanychangeinchromosomalnumber.Thespermatogoniamigrate
alongwithsertolicellstowardsthelumenofseminiferoustubule.
2.StageofGrowth:Atthisstage,theprimaryspermatocytegrowsintolarge
cells.Apartfromgrowththereisnootherchangeinspermatocyteduringthis
stage.
3.StageofMaturation:Afterreachingthefullsizeeachprimaryspermatocyte
quicklyundergoesmeioticormaturationdivision,whichoccursinto2phases.
Firstphase:Inthefirstphaseeachprimaryspermatocytedivideinto2
secondaryspermatocyte.Thesignificanceoffirstmeioticdivisionisthateach
secondaryspermatocytereceivesonlythehaploidorhalfthenumberof
chromososomes.23chromosomesinclude22autosomesandanXorY
chromosomes.
Secondphase:Duringthisphase,eachsecondaryspermatocyte
undergoessecondmeioticdivisionresultingin2smallercellscalledspermatids.
Eachspermatidhashaploidnumberofchromosomes.
4.StageofTransformation:Thereisnofurtherdivision.Thespermatidsare
transformedintomaturedspermatozoabymeansofspermeogenesisand
releasedbyspermination.
SPERMEOGENESIS:Spermatidsbecomematuredspermatozoa.Thechanges
takingplaceduringspermeogenesisare,
1.Condensationofnuclearmaterial
2.Formationofacrosome,mitochondrialspiralfilamentsandtailstructures
3.Removalofextraneouscytoplasm
SPERMINATION:Itistheprocessbywhichthematuredspermsarereleased
fromtheSertolicellsintothelumenofseminiferoustubule
FACTORSINFLUENCINGSPERMATOGENESIS:
1.FSH:Ithelpstheconversionofspermatidstosperm.
2.LH:StimulatestheLeydigcellstoproducetestosterone
3.Testosterone:Inhighconcentrationisessentialforgrowth,multiplication
andmaturation0fthegametes

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1 4.Temperature:Forspermatogenesis,lowtemperature(35C)required.This
lowtemperaturesituationisproducedasthetestisareoutsidetheabdominal
cavitieswithinthescrotumandduetocirculationofairaroundthescrotum
5.GHandotherhormonesnecessaryforgeneralmetabolismandgrowth
6.SeminalFluidswithitsfructosecontenthelpsinthematurationofsperms
7.VitaminE,CandseveralmembersofBcomplexarerequiredfornormal
spermatogenesis.
SEMEN
Semenisawhiteorgrayfluidthatcontainsspermatozoa.Itisthe
collectionoffluidfromtestes,seminalvesicles,prostateglandandbulbo
urethralglands.Semenisdischargedduringsexualactandtheprocessof
dischargeofsemeniscalledejaculation.
Atthetimeofejaculation,humansemenisliquidinnature.Immediately
itcoagulatesandaftersometimeitundergoesasecondaryliquefaction.
Whensemenisejaculated,thespermsarenonmotileduetotheviscosity
ofcoagulum.Whenthecoagulumdissolves,thespermbecomemotile.
PROPERTIESOFSEMEN
Volume :2-6ml/ejaculation
Sp.Gravity:1.028
pH :7.5
Reaction :Alkaline
COMPOSITIONOFSEMEN
Totalcountofspermisabout100-150million/mlofsemen.Sterility
occurswhenthespermcountfallsbelow20million/ml.Thoughthespermscan
bestoredinmalegenitaltractforlongerperiods,afterejaculationthesurvival
timeisonlyabout24-48hrsatatemperatureequivalenttobodytemperature.
Therateofmotilityofsperminfemalegenitaltractisabout3mm/minute.The
spermreachinthefallopiantubeinabout30-60minutesaftersexualintercourse.
Theuterinecontractionsduringsexualactfacilitatethemovementofsperms.
STRUCTUREOFSPERMATOZOON

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1 Spermatozoonisthemalereproductivecelldevelopedinthetestes.Itis
alsocalledthesperm.Thematuredspermatozoonis60micronslong.Each
spermatozoonconsistsof4parts
Head
Neck
Body
Tail

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1 1.HEAD:Ovalinshape,withalengthof3-5microns,andwidthofupto3
microns.Theheadisformedbyacondensednucleus,athincytoplasmanda
thincellmembrane.Theanterior2/3
rd
oftheheadislikeathickcapanditis
calledacrosome.Italsocontainshyaluronidaseandproteolyticenzymeswhich
areessentialforthespermtofertilizetheovum.
2.NECK:Theheadisconnectedtothebodybyashortneck.Itsanteriorendis
formedbythickdiscshapedanteriorendknob,whichisalsocalledproximal
centriole.Theposteriorendisformedbyanothersimilarstructureknownas
posteriorendknob.Theneckandbodyofspermstogethercalledmidpiece.
3.BODY:Itiscylindricalwithalengthof5-9micronsandthethicknessof1
micron.Thebodyofthespermconsistsofacentralcorecalledaxialfilament
coveredbythincytoplasmiccapsule.Theaxialfilamentstartsfromposterior
endknoboftheneck.Inthebody,theaxialfilamentissurroundedbyaclosely
woundspiralfilamentconsistingofmitochondria.
4.TAIL:Thetailofthespermconsistsof2segments.
I.TheChieforMainpieceoftail:Itisenclosedbycytoplasmiccapsuleandhas
anaxialthread.Itis40-50micronslong.
II.TheterminalorEndpieceoftail:Ithasonlytheaxialfilament
APPLIEDPHYSIOLOGY
Azoospermia:Lackofsperminsemen.
Oligozoospermia:Lowspermcountwith<20million.ml.
Teratozoospermia:Presenceofspermswithabnormalmorphology.
ENDOCRINEFUNCTIONSOFTESTES
Testessecretemalesexhormoneswhicharecollectivelycalledthe
androgens.Androgenssecretedbytestisare
Testosterone
Dihydrotestosterone
Androstenediene

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1 ActinandInhibinarealsosecretedintestis.Howeverthese2hormones
donothaveandrogenicfunction
FUNCTIONSOFTESTOSTERONE
Testosteronehas2importantfunctionsinadult
1.Effectonsexorgans:Itincreasesthesizeofpenis,scrotumandthetestes
afterpuberty.Alltheseorgansareenlargedat-least8foldsbetweentheonset
ofpubertyandtheageof20years,undertheinfluenceoftestosterone.
Testosteroneisalsonecessaryforspermatogenesis.
2.Effectonsecondarysexualcharacters:Secondarysexualcharactersarethe
physicalandbehavioralcharacteristicsthatappearatthetimeofpubertyin
humans.Thesecharactersdistinguishthemalefromfemale.
FEMALEREPRODUCTIVESYSTEM
Thefemalereproductivesystemconsistsoffollowingparts:
(1)Ovaries.Theovariesaretwoovalbodies(about30-40mmlong)located
belowandbehindtheuterinetubes.Eachovaryissupportedbyaseriesof
ligaments.Themainfunctionoftheovaryistoproduceeggs(ova)andthe
femalesexhormones,estrogenandprogesterone.Theyareattachedbya
membranetotheuterusandsuppliedwithbloodvessels.
(2)TheUterineTubes.Theuterinetubesconsistoftheproximalpartcalled
oviductsandthedistalpartcalledFallopiantubes.Theuterinetubesareattached

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totheovaries.Atthedistalendeachfallopiantubeexpandsintofunnellike
infundibulum,havingthefringelikeprojectionscalledfimbriae.Whenovaare
releasedfromtheovarytheypassdownthefallopiantube.Fertilizationnormally
occursintheFallopiantube.
(3)TheUterus.Bothoviductsopenintoawidertube,theuterus,orwomb,
whichmeasuresabout3inchesinlength,2inchesinwidthand1inchindepth.
Theuterusconsistsofadome-shapedportion,calledthefundus,acentral
taperingportion-thebodyandanarrowportionopeningintothevagina,called
thecervix.
(4)Thevaginaisacollapsiblemusculartube,about3incheslong,andcapable
ofgreatdistention.Atthelowerendofthevaginanormallythereisafoldof
mucousmembraneinthevirginalstate,thehymen,whichpartiallyclosesthe
orifice.Thevaginareceivestheseminalfluid,servesasthelowerpartofthebirth
canalandactsasanexcretoryductforuterinesecretionsandmenstrualflow.
(5)Thevulvaisacollectivenameforfemaleexternalgenitalia.Twofoldsofskin,
thelabiamajoraandthelabiaminor,enclosethevulvaattheentrancetothe
vagina.
(6)TheBartholin’sorvestibularglandsarepresentoneithersideofthevaginal
orifice,andsecretealubricatingfluid.
(7)Themammaryglands,orbreasts,arefunctionallyrelatedtothefemale
reproductivesystem,sincetheysecretemilkforthenourishmentoftheyoung.
OVARY

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0 Atransversesectionofanovaryshowsthatitconsistsofanoutercortex
andinnermedulla.Themedullacontainstheconnectivetissuecalledstroma,
bloodvesselsandnervefibers.Thecortexislinedbygerminalepithelium,below
whichtherearegroupsoffollicles,eachenclosinganegg.
Thecortexislinedexternallybyadensefibroustissue,thetunica
albuginea.Outofmanyfolliclespresentatbirth,only300to400folliclesreach
maturityandliberatetheirova(ovulation)duringthereproductiveyearsofa
humanfemale(pubertytomenopause).Oneofthedevelopingfollicles(primary
follicle,secondaryfollicle,maturingfollicle)formamaturefolliclecalledthe
Graafianfollicle.
GRAAFIANFOLLICLE
EachGraafianfolliclecontainstheovum.Immediatelysurroundingthe
ovumisalayeroffolliclecells,theinnerzonapellucidaandouterlayerof
columnarcells,thecoronaradiata.Thefolliclecontainsafluidfilledspacecalled
theantrum.Theantrumislinedbyfolliclecellswhichfromtwozones,the
membranagranulosaandthecumulusoophorus.TheGraafianfollicleis
surroundedbytwoconnectivetissuecelllayers,theouterthecaexternaandthe
innerthecainterna.Thefollicularcellssecretethehormoneestrogenwhich
controlsthemenstrualcycle.

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0 STRUCTUREOFHUMANOVUM
Humanovumoreggisaround,nonmotile,haploidfemalesexcell.Itis
about0.15mmindiameter.Thehumanovumisalecithal.Ithasalarge
centrallylocatednucleusanddensecytoplasm(ooplasm).Thecytoplasm
storesfoodmaterialsrequiredfortheentireprocessofdevelopment.The
ovumhas4envelopes,

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0 1.Plasmamembrane:Innermostlayer.
2.Vitellinemembrane:Thin,transparentlayeroutsidetheplasmamembrane
secretedbycytoplasmofovum.
3.Zonapellucida:Thick,transparentnon-cellularlayersecretedbyfollicle
cellsoftheovary.
4.Coronaradiata:Outermostcellularlayerofradiallyelongatedfolliclecells.

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0 FUNCTIONSOFOVARIES
1Oogenesis
2.Secretionoffemalesexhormones
3.Menstrualcycle
OOGENESIS
Theprocessofformationofovumiscalledoogenesis.Ittakesplacein
theGraafianfollicleofovary.Thematurefolliclecontainsadiploidprimary
oocyteatitscentre.Oogenesisstartsearlyintheembryonicstages.Ababy
girlisbornwithdefinitenumberofprimaryoocytesalreadyinprophaseIinthe
ovary.Furtherdevelopmentofprimaryoocytesremainsuspendedtillpuberty.
Oogenesisiscompletedonlyaftertheonsetofpubertyandonlyoneof500
diploidcellsisstimulatedbyFSHtomature.Sooogenesisisadiscontinues
process.
Oogenesisisdividedinto3phases.Theyare,
1.Phaseofmultiplication:Theinitialstepsineggproduction.Duringthe
phaseofmultiplication,thegerminalepithelialcellsoftheovaryundergo
rapidandrepeatedmitoticdivisionstoformgroupsofdiploideggmother
cellscalledoogonia.
2.Phaseofgrowth:Duringthephaseofgrowth,someoftheoogoniastop
mitoticdivision.Onefromeachfollicleabsorbs,synthesizeandstores
substances.Thesecellsgrowinsizeandformtheprimaryoocyte.
Thus,about45000to65000primaryoocytesareformed.Otheroogonia
surroundtheprimaryoocyteandtransformtofollicularepitheliumwhich
nourishtheprimaryoocyte.
3.Phaseofmaturation:Duringthephaseofmaturation,thediploidprimary
oocyteundergoesmeiosisItoform2unequalhaploidcells.Thelarger
celliscalledthesecondaryoocyteandthesmallerfragmentiscalledfirst
polarbody.Atthisstage,ovulationoccursandthesecondaryoocyteis

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entryofspermduringfertilization.Secondaryoocytethenundergoes
meiosisIItoform2unequalhaploidcells.Thelargercelliscalledootid
andthesmallercelliscalledsecondpolarbody.Thefirstpolarbody
dividesinto2polarbodies.Thepolarbodieshavenoroleinreproduction.
Theootidundergoesfurtherchangesanddevelopintoafunctionalegg
cellorovum.
OVARIANHORMONES
Ovariessecretethefemalesexhormonesestrogenandprogesterone,
inhibin,relaxinandsmallquantitiesofandrogens.
MENSTRUALCYCLE
Thecycliceventsthatthattakeplaceinarhythmicfashionduringthe
reproductiveperiodofwoman'slifeiscalledmenstrualcycle.Themenstrual
cyclestartsattheageof12-15yrs,whichmarkstheonsetofpuberty.The
menstrualcycleceasesattheageof45-50yrs.Thepermanentcessationof
menstrualcycleinoldageiscalledmenopause.Thedurationofthiscycleis
usually28days.Butundernormalphysiologicalconditions,itmayvary
between20&40days.Therearebasically3phasesinmenstrualcycle.They
areasfollows
Menstrualphase(1-5days)
Thefunctionallayeroftheendometriumbecomesdetachedfromthe
uterinewallandthisresultsinbleeding.Bloodlossisusuallybetween50-150ml.
Detachedtissuesandbloodpassthroughthevaginaasthemenstrualflow.
Proliferativephase(days6-14)
Aslevelsofestrogenincreasetheendometriumbeginstoproliferateand
thicken,tubularglandsandspiralarteriesform.Estrogenalsostimulatesthe
synthesisofprogesteronereceptorsinendometrialcells.Ovulationoccursatthe
endofthisphase.
Secretoryphase(days15-28)

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0 Risinglevelsofprogesteroneproducedbythecorpusluteumactonthe
endometriumstimulatingtheenlargementofglandswhichbeginsecreting
mucusandglycogeninpreparationforimplantationofthefertilizedovum.
Iffertilizationdoesnotoccur,thecorpusluteumdegenerates,
progesteronelevelsfallandtheendometriumdegenerates.Thecyclestarts
againwiththefirstdayofmenstrualflow.
OVARIANCYCLE
Duringeachovariancycle,upto20primordialfolliclesareactivatedto
beginthematurationprocess,butusuallyonlyonereachesfullmaturity,the
remainderregress
Theovariancyclecanbedividedinto3phases:.
1.Follicularphase
FrommanyprimordialfolliclesoneGraafianfollicledevelops.
2.Ovulatoryphase
TheGraafianfollicleisreleased.
3.Lutealphase
Thecorpusluteumandcorpusalbicansareproduced.
1.FollicularPhase
Folliculardevelopmentfromtheprimordialfolliclesisasfollows(Figure4):
1.Primaryfolliclestage:
Follicularepitheliumsurroundingtheoocytethickenstoformcuboidal
granulosacells,Zonapellucidaformsbetweentheoocyteandgranulosa
cells.
2.Growingfolliclestage:
Granulosacellsproliferateformingamultilayeredcapsulearoundthe
oocyte.Mostgrowingfolliclesregressanddie.
3.Antral(orsecondaryfollicle)stage:
Remainingfolliclestakeupfluidanddevelopacentralcavity(antrum).
Connectivetissuesurroundingthefolliclesforms2layers,aninnertheca

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0 internaandanouterthecaexterna.Cellsofthethecainternasecrete
oestrogen.Usually,onlyoneantralfolliclebecomesdominantand
enlarges.Therestdegenerate(atresia).
4.Graafianfolliclestage:
Thefirstmeioticdivisioniscompletedjustbeforeovulation.Theoocyteis
nowknownasthesecondaryoocyteandcommencesits2ndmeiosis.The
antrumenlarges.Thegranulosacellsaroundthesecondaryoocytesettle
attheedgeoftheantrumasthecumulusoopherus.Thefollicleisnow1.5
-2.5cmindiameter.
2.OvulatoryPhase
Oncefullydevelopedthegraafianfolliclebulgesfromtheexternalwallof
theovary.Ovulationoccurswhentheovarianwallrupturesandexpelsthe
secondaryoocyteintotheperitonealcavity.Thesecondmeioticdivisionofthe
oocyteiscompletedonlyafterpenetrationoftheoocyte(knownasanovum)by
aspermatozoon.
3.LutealPhase
Afterovulation,thegranulosacellsofthegraffianfollicleproliferateand
formthecorpusluteumwhichishighlyvascularizedandsecretesprogesterone
andestrogens.
Progesterone,fromthecorpusluteumpreparestheendometriumfor
implantation(seemenstrualcycle).Iffertilizationdoesnotoccurandanovum
doesnotimplantintotheuterinewall,thecorpusluteumdegeneratesandforms
thecorpusalbicans.
Ifimplantationdoesoccur,thedevelopingplacentasecreteshuman
chorionicgonadotrophin(hCG)whichpreventsdegenerationofthecorpus
luteumandprolongssecretionofprogesterone.After5-6weekstheplacentais
sufficientlydevelopedandtakesoverasthemainorganofprogesterone
secretion.
HORMONALCHANGESDURINGMENSTRUALCYCLE

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0 Duringtheovariancycle,growthanddevelopmentofthefollicleisdriven
bytwogonadotrophichormones:
1.FollicleStimulatingHormone(FSH)
2.Luteinisinghormone(LH)
BothFSHandLHaresecretedbytheanteriorpituitaryandareunderthe
controlofgonadotrophinreleasinghormone(GnRH)secretedbythe
hypothalamus.FSHandLHstimulatefolliclegrowth.Asthefolliclegrows,thecal
cellssecreteestrogens.Risinglevelsofestrogenintheplasmahavea
negativefeedbackeffectontheanteriorpituitaryinhibitingoutputofFSHandLH.
However,thisnegativefeedbackisonlytransientandaslevelsofestrogen
increasetheybegintohaveapositiveeffectonthehypothalamic-pituitaryaxis
resultinginaburstofLHand,toalesserextent,FSH.ThissuddenburstofLH
andFSHstimulatescompletionofmeiosisIintheprimaryoocyteandisalso
believedtobeinvolvedinstimulatingsynthesisofenzymesinvolvedinbulgingof
theovarianwall.
Afterovulation,LHpromotesthetransformationoftherupturedgraafian
follicleintothecorpusluteum.LHstimulatesthecorpusluteumtosecrete
progesteroneandestrogen.Progesteroneandestrogenfromthecorpusluteum
haveanegativefeedbackeffectontheanteriorpituitaryandinhibitFSHandLH
production.Thispreventsdevelopmentofnewfollicles.AsLHlevelsfall,the
corpusluteumbeginstodegenerate.Levelsofprogesteroneandestrogenfall.
FSHandLHareagainproducedbytheanteriorpituitaryandanewcyclebegins.

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0 Theprimarysexorgansareapairofovarieswhichproduceeggsorova
andsecretefemalesexhormones,theestrogensandprogesterone.The
accessorysexorgansinfemalesare:
1.Asystemofgenitalducts:Fallopiantubule,uterus,cervixandvagina.
2.Externalgenitalia:Labiamajora,labiaminoraandclitoris.

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