Clonal analysis of vertebrate myogenesis: III. Developmental changes in the muscle-colony-forming cells of the human fetal limb☆

[摘要] Thecelllineageofdevelopinghumanlimbmusclehasbeeninvestigatedbymeansofaninvitroclonalassay.Singlecellscapableofformingdifferentiatedmusclecolonieshavebeendetectedwithintheprospectivelegmuscleregionasearlyasthe36thdayofhumandevelopment(Streeter'sHorizonXVI).Atthisstageclonablemyoblastsaccountfor14%ofthetotalcolony-formingcells.Therelativeproportionofclonablemyoblastsincreasesrapidlyduringsubsequentfetaldevelopmentandattainsaplateaulevelofapproximately90%bythe100thdayofdevelopment.The90%plateaulevelpersistsatleastuntilday172.Bycorrelatingthepercentmusclecolonydifferentiationwithclonalplatingefficiencyandwiththenumberofsinglecellsderivedfromthetotallimbmuscleregionoffetusesofdifferentages,anestimateoftheactualnumberofclonablemyoblastswithinthedevelopinglimbmusculatureisobtained.Sequentialchangeswithinthemusclecelllineagehavebeenfurtherdissectedbythetemporalanalysisofage-dependentmediumeffectsonmusclecolonydifferentiation.Theanalysisindicatesthatclonablemyoblastsderivedfromearlyfetusesaresensitivetomediumconditionstowhicholdermuscle-colony-formingcellsarerelativelyinsensitive.Inaddition,fusingandnonfusingcolonieshavebeenclassifiedintorecognizablemorphologicaltypeswhoserelativeproportionsareobservedtochangeduringlimbdevelopment.Theresultsarecorrelatedwithhumanlimbmorphogenesisandskeletalmusclehistogenesisandanoperationalmodelofmusclecelllineageisproposed.

[学科分类] 生物科学（综合）