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Gastrulation – - University of Minnesota Duluth pschoff/documents/Gastrulation-chickfish...Zebrafish gastrulation hypoblast formation – ingression and/or involution of deep cells

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  • GastrulationChick,Fish,Mammal

    DevelopmentalBiologyBiology4361

    November15,2005

  • Haffteretal.,1996

    Zebrafishgastrulationblastodisc

  • Figure10.21

    Zebrafishgastrulation

    hypoblastformationingressionand/orinvolutionofdeepcells

    embryonicshield

    ENL periderm(extraembryonicprotectivemembrane)

    epiblast ectoderm

    hypoblast mesendoderm(mesodermandendodermprecursors)

    YSL endoderm

  • Figure10.22

    Zebrafishembryonicshield

    drivenbyYSL

    Embryonicshieldfunctionallyequivalenttoamphibiandorsallipoftheblastoporecanorganize2axiswhentransplanted

  • Haffteretal.,1996

    Zebrafishgastrulationblastodisc yolksyncytiallayer epiblast

    hypoblast

    somite

    notochord

    somite

  • Figure5.16

    epiblastformsallthreegermlayers(plusextraembryonicmembrane)

    hypoblastformsextraembryonicendoderm

    Chickcleavage

    delaminationmigration

    areapellucida

    areaopaca

    differentfromfishhypoblastformsprimordialgermcells

    doesnotformanyembryonicendodermormesoderm

  • Figure10.23

    Gastrulationchick

    areapellucida=innertransparentportionoftheblastodermabovesubgerminalspace

    areaopaca =opaqueperipheralareacellsincontactwithyolk

    gastrulationstartswithextensivecellrearrangementsinposteriorepiblast

    cellsmovetomidlineandtheforwardprimitivestreak

  • Gastrulationchick

    majorgastrulationeventsoccurattheprimitivepit&primitivegroove

    elongationofprimitivestreakandformationofprimitivegroove&primitivepit

    anteriorendofprimitiveridgesarethickened=Hensensnode

    functionalequivalentofamphibianblastopore

  • Figure10.24

    involutioningression

    futureendodermingressfirstdisplacehypoblast

    Chickgastrulation

  • Chickgastrulation

    futuremesoderm(axial,paraxial,lateral)cellsingressfromanteriorendofprimitivepit

    epithelialtomesenchymaltransformation

    {

    extraembryonicmembranessurroundyolkectodermspreadbyepibolyhypoblastcellsspreadalongyolksurfacemesodermcellsinbetween

  • Figure10.26

    Gastrulation fatemapchick

  • Figure10.27

    Chick24h

  • Chickendevelopment1

    headregionstartstoliftofftheyolk

  • Chickendevelopment2

    ventralclosureofthebodyproceedsfromanteriortoposterior

  • Chickendevelopment3

    ventralclosureofthebodyiscompleted

  • Chickendevelopment

    extraembryonicmembranesandextraembryonicbloodvesselscompletelysurroundtheyolk

    yolksacisconnectedtothegutbyanarrowbridge

    aftercompletedventralclosure,embryorestsontopoftheyolksac

  • Earlymammaliandevelopmentnotverywellstudied:smalleggsdifficulttomaintaininculturebeyondblastocyststageethicalissues

    Figure5.11innercellmass&trophoblastareequivalentto

    epiblast&hypoblastofthechickenembryo

    Mammaliancleavage

    holoblasticcleavageresultsinablastocyst:

    hatchingfromzonaimplantationinuterusplacentaformation

    trophoblast

    embryo

    innercellmass

  • Earlydevelopmentinmammals

    Figure5.8

    embryoenterstheuterusinthemorulastageblastocyststagemakescontactwithuterusbeforeimplantationintouterus,theembryoshedszonapellucida

    Human:06days

  • GilbertSF,DevelopmentalBiology,6thed,Sinauer,2000

    hatchingofamouseblastocystfrom

    thezonapellucida

    Earlydevelopmentinmammals

    mouseblastocystenteringtheuterus

    initialimplantationoftheblastocyst(rhesusmonkey)

  • Earlydevelopmentinmammals

    GilbertSF,DevelopmentalBiology,7thed,Sinauer,2003

    amnioticcavitybeginstoform

    resultsinepiblast&hypoblast

    innercellmassdelaminateshypoblastcellsthatlinetheblastocoel,formingextraembryonicendoderm

    trophoblastdividesinto:

    syncytiotrophoblastfurthersprogressionoftheembryointouteruswallbydigestinguterustissue

    cytotrophoblastanchorsembryotouterustissue

    Human:711days

  • Earlydevelopmentinmammals

    GilbertSF,DevelopmentalBiology,7thed,Sinauer,2003

    extraembryonicmesodermformsitwilldevelopintotheextraembryoniccoelom

    embryoisnourishedbymaternalblood

    uterussendsadditionalbloodvessels

    cytotrophoblastenzymaticallyremodelsmaternalbloodvessels(trophoblasticlacunae)

    twolayeredblastodiscsimilartothatinbirdsembryonicepiblast&hypoblast

    epiblastdelaminatestheamnioticectodermthatsurroundstheamnioticcavity

    Human911days

  • Figure10.31

    Humanblastocyst12d

  • cellsingressandinvolutealongtheprimitivegrooveandatHensensnode

    GilbertSF,DevelopmentalBiology,6thed,Sinauer,2000

    Gastrulationinmammals

    formendoderm(replaceshypoblast)andmesoderm

  • Figure10.32

    Humangastrulation16d

  • Figure10.30

    Primategermlayerderivatives

    embryoproper