A radioautographic analysis of the migration and localization of trunk neural crest cells in the chick☆

[摘要] Theearlymigrationandlocalizationofneuralcrestcellshasbeenanalyzedradioautographically.Tritiatedthymidinewasusedasamarkertodistinguishthemorphologicallyundifferentiatedneuralcrestcellsfromthetissuesthroughwhichtheymoveandwasfoundtobewellsuitedasacell-specific,long-term,nontoxicmarkerinvivo.Theearlymigrationofneuralcrestoccursastwostreamsofindividualcells—oneleadingdorsolateradintothesuperficialectoderm,theotherventradinthemesenchymebetweentheneuraltubeandthemyotome.Thedirectionofthislattermigrationisindependentofthemesenchyme.Theorientationoftheinitialmigrationisrelatedtotheorientationofthegraftneuraltube.Metamerismofneuralcrestderivativesistheresultoftheenhancedearlymigrationofsomecellswithinthesegmentalsomiticmesenchymeandtheconcomitantattenuationofmigrationintersegmentally.Theneuralcrestoriginofspinalganglia,sympatheticneuroblastsandmelanoblastswasconfirmedbythistechnique.SomeSchwannsheathcells,however,wereshowntoemergefromtheneuraltubealongwiththeventralnervefibers,andthepossibilityisraisedthatsheathcellsareneurogliasolelyofneuraltubeorigin.Itisconcludedthatthenormalmigratorypathwayofintegumentalmelanoblastsiswithinthesuperficialectoderm.Thelabeledcellswhicharefirsttomigratethroughthesomiticmesenchymeappeartohavelocalizedatthedorsolateralmarginoftheaortaveryearlyindevelopment,andthesearethoughttobepresumptivesympatheticneuroblasts.Entericpigment-formingcellsarepresumedtoariseafterthefourthdayofincubationasanextensionoftheventralmigrationofsomeneuralcrestcellsbeyondtheareaofthesympatheticcomplex.Theroleoftheneuraltubeisdiscussedwithregardtoitseffectonthesegmentationofspinalgangliaandthepossibilitythatitsomehowpromotesthedifferentiationofganglionicneuroblastsfrompluripotentneuralcrestcells.

[学科分类] 生物科学（综合）