Effects of an “inside-out” limb-bud ectoderm on development of the avian limb☆

[摘要] Leg-budmesodermofthe3-daychickembryowasencasedininside-outwingorlegbudectodermandgraftedtothesomiteregionofahostchickembryo.Ineachcasetheinvertedapicalridgeoftheectodermoverlaidthemesodermalapex.Thenormalinside-outsidehistologyoftheectodermwasrestoredinafewhours,but3daysormorewererequiredbeforetheapicalectodermalridgeregaineditsnormalappearance.Meanwhile,however,growthoftherecombinantsresumed24hraftertheoperation,resultingintheformationoflegswithskeletalpartsinnormalproximodistalorder.Inallcaseswhereidentifiable,theanteroposterioraxisofthefootcorrespondedtothatofthemesoderm,butitsdorsoventralaxisconformedtothedorsoventralpolarityoftheectoderm.Theseresultsareessentiallyidenticalwiththoseobtainedwhenright-side-outectodermalhullsareusedinmakingrecombinants.Theectodermis,therefore,capableofexercisingitscharacteristicmorphogeneticeffectsbothduringandafterthereorganizationthatfollowsitsinversion.Mostimportantlytheseresultssuggestthattheactionoftheapicalectodermalridgeinpromotingproximodistalgrowthdoesnotrequiretheconstantexpressionofitsusualconfiguration.

[学科分类] 生物科学（综合）