A microphotometric study of myogenic lizard cells grown in vitro1☆

摘要

Earlysubculturesofpredominantlymyogeniccellsfromtheregeneratingtailofthelizardappeartogiverisetotwotypesofcolonies.Beginningonday5to7,approximately85%ofthecoloniesinSeries2showedagradualaccumulationofrounded-upcellspreviouslyidentifiedasprefusionpresumptivemyoblasts.Theother15%neverhadanyrounded-upcellsbut,rather,weremadeupoflargespreadingcellswithlargemultinucleatenuclei.Microphotometricmeasurementsshowedthattherounded-upcellswerediploid,thusconfirmingthattheywerenotsynthesizingDNAanddemonstratingthattheyhadwithdrawnfromthemitoticcycleinG1.TheflattenedcellsinthecolonieswiththeroundedupcellsweretypicalofadividingcellpopulationwithFeulgen-DNAvaluesshowing2Cand4Cpeakswithaspreadofintermediatevalues.ThecoloniescontainingonlylargespreadingcellshadFeulgen-DNAvalueswithpeaksatapproximately4Cand8C.Thisimpliedthatthelargecellsmightbeadividingtetraploidpopulationassuggestedbykaryotypingexperimentsreportedelsewhere.Autoradiographicstudiesusinga30-minutepulseoftritiatedthymidineconfirmedthattherounded-upcellsarenotsynthesizingDNAandshowedthattheflattenedcellscontainasynthesizingpopulation.