组织学与胚胎学 胚胎学2课件

Germdiscformanddifferentiate

胚层的形成和分化1、Developmentofthebilaminargermdisc（二胚层的形成,2w）：(1)二胚层胚盘（bilaminargermdisc)。上胚层（epiblast）

下胚层（hypoblast）

羊膜腔（amnioticcavity)，卵黄囊(yolksac)。

羊膜腔上胚层下胚层卵黄囊体蒂（bodystalk)(3)Theformationoftheyolksac（卵黄囊形成）初级卵黄囊胚外中胚层的网状组织Ondays10to11,anacellularextraembryonicreticulumformbetweenHeuser’smembraneandthecytotrophoblast.下胚层形成次级卵黄囊(4)Thehypoblastgivesrisetotheextraembryonicendodermthatlinestheprimaryyolksac(5)Thechorioniccavityisproducedinconjunctionwiththedevelopmentoftheextraembryonicmesoderm(6)Thedefinitiveyolksacisformedbyanewwaveofcellsthatmigratefromthehypoblastanddisplaceheuser’smembrane2、三胚层的形成(第3周）(1)Theprimitivestreakappearsatthebeginningofthethirdweek(原条的出现,3w)

原条

primitivestreak原结primitivenode

原凹primitivepit原沟primitivegroove口咽膜胚盘脊索突原结原条泄殖腔膜中胚层(2)Thedefinitiveendoderm（内胚层）andintraembryonicmesoderm（胚内中胚层）formthroughtheprimitivestreakTheprimitivestreakretreatsanddisappears,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：三胚层第四周：圆柱体Meningohydroencephalocele(脑积水脑膜脑突出）Thisanomalymayformthroughdefectiveossificationoftheoccipitalboneandprobablyisnotaconsequenceofdefectiveclosureoftheneuraltube.Headlessmice.Thedevelopmentandmaintenanceofthe“headorganizingcenter”requirestheexpressionofthehomeoboxgeneLim-1.KnockoutofLim-1resultsinheadlessmice.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)神经嵴周围神经系统

肾上腺髓质

分化外胚层分化(3)表面外胚层:皮肤表皮及其附属器2、mesodermdifferentiate(中胚层的分化)：（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，大部分中轴骨和骨骼肌。（2）intermediatemesoderm(间介中胚层)——位于体节外侧

，泌尿生殖系统发生的原基。3、Endodermdifferentiate(内胚层的分化)：随胚体的卷曲，内胚层形成原始消化管，内胚层：是消化系统、呼吸系统和中耳、甲状腺、

甲状旁腺、扁桃体、胸腺，膀胱和尿道等上皮的原基。口咽膜咽囊前肠肺芽中肠后肠泄殖腔围心腔尿囊管肛膜五周人胚四周人胚围心腔咽囊胃肝中肠袢后肠肝隙室五、胚胎外形的建立及演变1、胚体的形成五周鳃弓全，视杯与听泡。六周手指见，耳廓小苗苗。七周体伸直，颜面形成了。八周成人形，肢体头面俏。三月分男女，四月能打闹。五月爱运动，胎心可听到。六月见指甲，皮红