Experimental analysis of the mechanisms of somite morphogenesis

[摘要] Earlierstudieshavesuggestedinfluencesonsomitemorphogenesisby“somite-formingcenters,”primitivestreakregression,Hensen'snodeandnotochord,andneuralplate.Contradictionsamongthesestudieswereunresolved.Ourexperimentsresolvetheseconflictsandrevealrolesoftheprimitivestreakandnotochordinshearingtheprospectivesomitemesodermintorightandlefthalvesandreleasingsomite-formingcapabilitiesalreadypresent.Theneuralplateappearstobetheprincipalinductorofsomites.Embryofragmentscontainingnosomite-formingcenters,node,notochord,orstreakneverthelessformedsomiteswithin10hr.Suchsomitesdispersewithinthenext14–24hr,whichmayexplainwhyothersfailedtoseethem.Inthesefragments,anincisionalongsidethestreaksubstitutesforstreakregressioninreleasingsomiteformation.Allsuchsomitesformsimultaneouslyratherthaninthenormalanteroposteriorprogression.Thesefragmentscontainneuralplate,butnotnotochord.Webelievethatphysicalattachmentofsomitestonotochordinnormalembryosstabilizesthemandpreventsdispersal.Piecesofepiblastwererotated180°puttingneuralplateoverlateralplatemesodermregions.Somiteswereinducedfromthelateralplatebythedisplacedneuralplateregion.Thisisadditionalevidenceofthepowerfulabilityofneuroepitheliumtoinducesomites.

[学科分类] 生物科学（综合）