REPRODUCTION AND EMBRYONIC DEVELOPMENT - Great 生殖和胚胎发育的大

REPRODUCTIONANDEMBRYONICDEVELOPMENT

Sexualandasexualreproductionarebothcommonamonganimals

REPRODUCTIONthecreationofnewindividualsfromexistingones

ASEXUALREPRODUCTIONcreatingofoffspringwhosegenesallcomefromoneparentwithoutthefusionofeggandsperm

BUDDINGsplittingoffofnewindividualfromexistingones

FISSIONoneindividualseparatesintotwoofaboutequalsize

FRAGMENTATIONbreakingofparentbodyintoseveralpieces

MustbeaccompaniedbyREGENERATION

REGENERATIONregrowthofbodyparts

SEXUALREPRODUCTIONthecreationofoffspringbythefusionoftwohaploidsexcells

GAMETESsexcells(n)

ZYGOTEfertilizedegg(2n)

SPERMmalegamete

OVUM(UNFERTILIZEDEGG)femalegamete

HERMAPHRODITISMorganismhasbothmaleandfemalereproductivesystems

Aidsnon-mobileandsolitaryorganisms;helpsinfindingmates

EXTERNALFERTILIZATIONfusionofgametesoutsideofbody

INTERNALFERTILIZATIONfusionofgametesinsideofbody

COPULATIONsexualintercourse

Reproductiveanatomyofthehumanfemale

OVARIESeachaboutaninchlong,withabumpysurface

FOLLICLESconsistofsingledevelopingeggcellsurroundedbyoneormorelayersoffolliclecellsthatnourishandprotectthedevelopingeggcell

Folliclecellsproduceestrogen

Awomanisbornwith40,000–400,000follicles;onlyseveralhundredgetreleased

OVULATIONprocessthatejectstheeggcellfromthefollicle;occursaboutevery28days

CORPUSLUTEUMformsafterovulation,remainingfolliculartissuegrowswithinovarytoformasolidmass

Secretesprogesterone;hormonethathelpsmaintainuterinelining

Ifeggisnotfertilized,corpusluteumdegenerates

OVIDUCTa.k.a.FALLOPIANTUBE;leadstheeggtotheuterus;thisiswherefertilizationactuallyoccurs

UTERUSa.k.a.WOMB;actualsiteofpregnancy;onlyabout3inchesinawomanwhohasneverbeenpregnantbutcanexpand

ENDOMETRIUMinnerliningoftheuterus;embryogetsimplantedhere

EMBRYOtermusedtodescribezygote(fertilizedegg)untilbodystructuresbegintoappear(about9weeks)

FETUStermgiventodevelopingoffspringfrom9thweekuntilbirth

ECTOPICPREGNANCYembryoimplantsinthewrongplace;somewhereotherthantheuterus;canbefatalifnottreated

CERVIXneckoftheuterus;openstovagina

VAGINAthinwalled,butstrong,muscularchamberthatservesasthebirthcanalthroughwhichthebabyisexpelled

Alsoaccommodatesmale’spenisandisrepositoryforspermduringcopulation

LABIAMINORAandLABIAMAJORAprotectthegenitalregion

HYMENthinmembranecoveringthevaginalopening;functionnotknown

BARTHOLIN’SGLANDnearvaginalopening;secreteslubricatingfluidduringsexualarousal,asdoesthevaginallining

Severalfemalereproductivestructuresareimportantinsexualarousal

Vagina

LabiaMinora

CLITORISsolefunctionissexualarousal

GLANS“head”;enormousnumberofnerveendingsmakingitverysensitive

PREPUCEsmallhoodofskin

Reproductiveanatomyofthehumanmale

TESTESmalegonads;housedoutsidetheabdominalcavity

SCROTUMsacthathousesthetestes;maintainscurrentbodytemperatureforspermproduction

EPIDIDYMIScoiledtubethatstoresspermwhiletheydevelop

EJACULATIONexpulsionofsperm-containingfluidoutofpenis,thisiswhenspermleavetheepididymis

VASDEFERENSductthatgoesfromepididymistoejaculatoryduct

EJACULATORYDUCTfusionof2vasdeferensandductfromseminalvesicle

Malereproductivesystemhas3setsofglands

SEMINALVESICLEsecreteathick,clearfluidthatprotectsandnourishesthesperm

PROSTATEGLANDsecretesamilky,alkalinefluidthatbalancestheacidityofanytracesofurineintheurethraandhelpsprotectthespermfromthenaturalacidityofthevagina

BULBOURETHRALGLANDSmayhelplubricateurethra,helpingspermmovethroughit

SEMENspermandglandularsecretionsmakethisfluidthatisdischargedduringorgasm

95%glandularfluid;5%sperm(200–500million)

PENISconsistsmainlyoftissuethatcanfillwithbloodtocauseanerectionduringsexualarousal;makinginsertionintovaginapossible,alongwithtransferofsperm

GLANS“head”;manynerveendings,verysensitive

PREPUCEcovers“head”(GLANS);removedduringcircumcision

Ejaculationoccursin2stages

Spermandseminalfluidareforcedtowardsurethraregion;bladdersphinctershutstopreventurinefromentering

Expulsionstageoccurswhenurethraregioncontractsandforcessemenalongpenis;thanmusclesinpeniscontractandexpelsemenoutofbody

Theformationofspermandovarequiresmeiosis

SPERMATOGENESIStheformationofspermcells

Takesabout65–75daysinthehumanmale

SEMINIFEROUSTUBULEScoiledtubesinthetesteswherespermdevelop

PRIMARYSPERMATOCYTESthecellsthatundergomeiosis

SECONDARYSPERMATOCYTESresultsofmeiosisIofprimaryspermatocyte

OOGENESISthedevelopmentofanovum

PRIMARYOOCYTEdormantdiploidcellinthefollicle

FSHstimulatesmeiosis

SECONDARYOOCYTEthehaploidcell;unequaldivisionofcytoplasm

1ovum(mostofcytoplasm;1polarbody(almostnocytoplasm)

Hormonessynchronizecyclicalchangesintheovaryanduterus

OVARIANCYCLEeventsthatoccuraboutevery28daysinthehumanovary

MENSTRUALCYCLErelatedeventsintheuterus;controlledbyhormones

Anoverviewoftheovarianandmenstrualcycles

Ovariancyclehastwophases

Pre-ovulatoryphasefolliclegrowing

Post-ovulatoryphasefolliclehasbecomecorpusluteum

Menstrualcycle

Menstruationuterinebleeding(3–5days)

Aftermenstruation,theendometriumregrows(20–25days)

Hormonaleventsbeforeovulation

FSHandLHarereleased;estrogenlevelslowlybuildsupuntilithitsitpeak(ovulation)

Hormonaleventsatovulationandafter

LHpeaks,causingovulation(releaseofovumanddevelopmentofcorpusluteum)

CausehighlevelsofestrogensandprogesteronewhichinhibitFSHandLHproduction,notallowingotherfolliclestodevelop

Controlofthemenstrualcycle

Controlledonlybyestrogenandprogesterone

Thehumansexualresponseoccursinfourphases

FOURPHASES

EXCITEMENTPHASE

PLATEAUPHASEincreasedbreathingandheartrate

ORGASMrhythmiccontractionsofreproductivestructures

RESOLUTIONPHASEreversesthepreviousresponses;returntonormal

Sexualactivitycantransmitdisease

SEXUALLYTRANSMISSABLEDISEASES(STDs)contagiousdiseasespreadbysexualcontact

Contraceptionpreventsunwantedpregnancy

CONTRACEPTIONthedeliberatepreventionofpregnancy

3ways

Preventingreleaseofgametesfromgonads

Preventingfertilization

Preventingtheembryofromimplantingintheuterus

STERILIZATION

VASECTOMYvasdeferensarecut

TUBALLIGATIONoviductiscut

RHYTHYMMETHODorNATURALFAMILYPLANNINGtemporaryabstinence;refrainingfromintercourseduringthedaysaroundovulation

WITHDRAWALremovingpenisbeforeejaculation

SPERMICIDESspermkillingchemicals

INTRAUTERINEDEVICES(IUDs)smallplasticormetalobjectsinsertedintouterinecavitytopreventimplantation

MORNINGAFTERPILLS(MAPs)preventfertilizationorimplantationabout75%ofthetime

Fertilizationresultsinazygoteandtriggersembryonicdevelopment

FERTILIZATIONtheunionofspermandeggtoformadiploidzygote

Thepropertiesofspermcells

ACROSOMEmembrane-enclosedsacattheheadofthespermthatcontainsenzymesthathelpthespermpenetratetheegg

Neckcontainsmitochondrion

Flagellumprovidesmovement

Theprocessoffertilization

Thespermapproachestheegg

Thesperm’sacrosomalenzymesdigesttheegg’sjellycoat

Proteinsonthespermheadbindtoeggreceptors

Theplasmamembranesofspermandeggfuse

Thespermnucleusenterstheeggcytoplasm

AFERTILIZATIONENVELOPEFORMS

Anotherbarrierimpenetrabletosperm

Cleavageproducesaballofcellsfromthezygote

CLEAVAGEarapidsuccessionofcelldivisionsthatproducesaballofcells–amulticellularembryo–fromthezygote

BLASTOCOELfluid-filledcavityinthecenteroftheembryo

BLASTULAhollowballofcellsthatresultswhencleavageisfinished

Gastrulationproducesathree-layeredembryo

GASTRULATIONsecondmajorphaseofembryonicdevelopment;addsmorecellstotheembryo;sortsthecellsintodistinctcelllayers

GASTRULAthree-layeredstageoftheembryo

ECTODERM

ENDODERM

MESODERM

Organsstarttoformaftergastrulation

NOTOCHORDcartilaginoussupportfordevelopingtissues

NEURALTUBEbrainandspinalcord

SOMITESblocksofmesodermthatgiverisetosegmentalstructures

COELOMhollowspace;bodycavity

Changesincellshape,cellmigration,andprogrammedcelldeathgiveformtothedevelopinganimal

PROGRAMMEDCELLDEATH(APOPTOSIS)timely,tidysuicideofcells

Necessarytocreatespacesbetweenfingersandtoes

Embryonicinductioninitiatesorganformation

INDUCTIONthemechanismbywhichonegroupofcellsinfluencesthedevelopmentofanadjacentgroupofcells

Patternformationorganizestheanimalbody

PATTERNFORMATIONtheemergenceofabodyformwithspecializedorgansandtissuesallintherightplaces

Theembryoandplacentatakeshapeduringthefirstmonthofpregnancy

GESTATION“pregnancy”;thecarryingofdevelopingyoungwithinthefemalereproductivetract

Anoverviewofdevelopmentalevents

BLASTOCYSTmammalianequivalentofablastula

TROPHOBLASTouterlayerthatallowsforuterineimplantation

PLACENTAcombinationoftrophoblastandmaternalcells

EXTRAEMBRYONICMEMBRANES

AMNIONprotectivefluid

YOLKSACnoyolkinhumans,butsamename;nourishmentfornon-placentals

CHORIONbecomeembryospartoftheplace