《基因的分子生物学》第21章 模式生物（英语教学课件）非AI生成.ppt

Themousehasvirtuallysamecomplementofgenesasthosepresentinthehumangenome:eachcontainsapproximately30000genesandthereisaone-toonecorrespondenceformorethan85%ofThesegenes.*MouseEmbryonicDevelopmentDependsonStemCellsThefirstobviousdiversificationofcelltypesisatthe16-cellstage,calledthemorula(桑椹胚).Thecellsinouterregionsofthemoruladevelopintotheplacenta(胎盘).Cellsininternalregionsgeneratetheinnercellmass(ICM)*TheICMcellscanbeculturedandinducedtoformanyadulttypeuponadditionoftheappropriategrowthfactors.Humanstemcells:offerthepromiseofprovidingarenwablesourceoftissuestoreplacedefectivecellsinvarietyofdegenerativediseasessuchasdiabetesandAlzheimer’s****Atthe64-cellstage(about3-4weeksaftergertilization)themouseembryo,calledablastocyst(胚泡),isreadyforimplantation.Thereareonly13ICMcellsformallthetissuesoftheadultmouse.TheICMistheprimesourceofembryonicstemcells.*Interactionsbetweentheblastocystanduterinewallleadtotheformationoftheplacenta.Shortlythereafter,afetusemergesthatcontainsabrain,aspinalcord,andinternalorgans(eg:heartandliver).*ThefirststageingastrulationisthesubdivisionoftheICMintotwocelllays:aninnerhypoblast(下内胚层)andanouterepiblast(上外胚层).Thentheembryoentersgastrulation(原肠胚),andtheICMformsallthreegermlayers:endoderm(内胚层),mesoderm(中胚层),ectoderm(外胚层).*Thenagroovecalledprimitivestreak(原条)formsalongthelengthoftheepiblast(上外胚层)andthecellsthatmigrateintothegrooveformtheinternalmesoderm.Theanteriorendoftheprimitivestreakisthenode.*Node;sourceofsignalingmoleculaes(includingtwosecretedinhibitorsofTGF-βsignaling,ChordinandNoggin)Double(bothgenes)mutantmouseembryosthatlackheadstructuresuchasforebrainandnose.*ItisEasytoIntroduceForeignDNAint