组织学与胚胎学胚胎学体蒂(2)Theamnioticcavitydevelopswithintheepiblast(3)Theformationoftheyolksac(卵黄囊形成)下胚层形成次级卵黄囊(4)Thehypoblastgivesrisetotheextraembryonicendodermthatlinestheprimaryyolksac(5)Thechorioniccavityisproducedinconjunctionwiththedevelopmentoftheextraembryonicmesoderm(6)Thedefinitiveyolksacisformedbyanewwaveofcellsthatmigratefromthehypoblastanddisplaceheuser’smembrane2、三胚层得形成(第3周)(1)Theprimitivestreakappearsatthebeginningofthethirdweek(原条得出现,3w)原条primitivestreak原结primitivenode原凹primitivepit原沟primitivegroove两胚层胚盘背面观口咽膜Significance:Theappearanceoftheprimitivestreakestablishesthelongitudinalaxisandthusthebilateralsymmetryofthefutureadultanddecideembryoorientation1、确定了中轴2、确定头尾方向3、就是胚体得组织中心(2)Thedefinitiveendoderm(内胚层)andintraembryonicmesoderm(胚内中胚层)formthroughtheprimitivestreak12theectoderm外胚层Theprimitivestreakretreatsanddisappears,andthecaudaleminencegivesrisetocaudalstructuresofthebody、(15-26day)ThemechanicsofgastrulationarenotwellunderstoodThefateofgastrulationepiblastcellscanbepredictedfromtheirsiteoforigin、Studymethod:Celltracingandcelllineage(细胞系)studies(3)Thenotochord(脊索)isproducedbycellsthatingressthroughtheprimitivenodePrimitivepot(原结)TheNotochordalprocess(脊索突)thenotochordalplate(脊索板)thenotochord(脊索)意义:决定胚体中轴诱导外胚层形成神经板椎间盘中髓核。Theultimatefateofthenotochordisdebated、Mesodermisexcludedfromthebuccopharyngealandcloacalmembrances、小结:胚胎发育:第一周:植入第二周:二胚层第三周:三胚层四、三胚层得分化Meningohydroencephalocele(脑积水脑膜脑突出)Thisanomalymayformthroughdefectiveossificationoftheoccipitalboneandprobablyisnotaconsequenceofdefectiveclosureoftheneuraltube、Headlessmice、Thedevelopmentandmaintenanceofthe“headorganizingcenter”requirestheexpressionofthehomeoboxgeneLim-1、KnockoutofLim-1resultsinheadlessmice、Fig4-12小结:神经系统、脑垂体、松果体、皮肤:表皮、附属结构凹陷上皮:口、鼻、肛门、外耳道、膜迷路、角膜上皮、视网膜、晶状体肾上腺髓质、腮腺上皮2、mesodermdifferentiate(中胚层得分化):(1)paraxialmesoderm(轴旁中胚层)——(somites)体节,第5周全部形成,共42-44对,分化为真皮,大部分中轴骨与骨骼肌。(2)intermediatemesoderm(间介中胚层)——位于体节外侧,泌尿生殖系统发生得原基。(3)lateralplatemesoderm(侧中胚层)——分两层A:Par