An analysis of melanogenesis in cultured chick embryo spinal ganglia☆

[摘要] Whensensorygangliaareremovedfromthe4-daychickenembryoandculturedinvitro,somecellsappearafterseveraldaysinculturewhichcontainmelaninpigment.Pigmentcelldifferentiationoccurslessfrequentlyinculturesofslightlyolderganglia,anddoesnotoccuratallinculturesofgangliaexplantedfromembryosolderthan6days.Fromtheseresultsandotherconsiderations,weconcludethatsomecellsinthenascentganglionproducepigmentinvitrowhentheywouldnotnormallydosoinsitu.Ithasbeensuggestedthatthedegreeofdispersionmayinfluencethedifferentiationofpluripotentneuralcrestcells(WestonandButler,1966).Thefacts(1)thatconditionsinculturepromotethedisruptionofthestructuralintegrityoftheexplantedganglionandthedispersionofitscells,and(2)thatpigmentusuallyappearsintheperipheraloutgrowthsofsuchcultures,areconsistentwiththissuggestion.Themechanismbywhichdispersionmighteffectexpressionofthepigmentphenotypeisnotknown.GanglionculturesweretreatedwithactinomycinD(AD)andcytosinearabinoside(CA)todiscriminatebetweenthepossibilities(1)thatthecapacitytomakepigmentexistedinsomecellsoftheganglionatthetimeofexplanationand(2)thatthiscapabilityaroseinsomeofthesecellsasaconsequenceoftheenvironmentalconditionsinvitro.TheappearanceofpigmentcellsinculturesofyoungsensorygangliaissensitivetoADandCAduringthefirstfewdaysinculture,butbecomesrelativelyinsensitivetosuchtreatmentlaterinthecultureperiod.Theseresultssuggestthatsomedevelopmentallysignificantevents,presumablyinvolvingDNAsynthesisandperhapssomeDNA-dependentRNAsynthesis,mustoccurduringthefirstfewdaysinculturebeforethepigmentphenotypemaybeexpressedbycellsintheculturedganglion.

[学科分类] 生物科学（综合）