Supernumerary limbs in amphibians: Experimental production in Notophthalmus viridescens and a new interpretation of their formation☆
[摘要] Theformationofsupernumerarylimbswasstudiedintheadultnewt,Notophthalmusviridescens.Forelimbblastemasatthestagesofmediumbudandearlydigitswereeithertransplantedtothecontralateralforelimbwiththeirdorsal-ventralaxisopposedtothatofthelimbstump,orremoved,rotatedthrough180°,andreplacedonthesamelimbstumpwithbothdorsal-ventralandanterior-posterioraxesopposedtothoseofthestump,orasacontrol,removed,andreplacedinnormalorientation.Supernumerarylimbswereproducedinbothexperimentalseries,butnotinthecontrols.Followingcontralateraltransplantation,supernumerarylimbsaroseclosetothegraftjunctionatthetwopositionswheredorsallimbtissuewasincontactwithventrallimbtissue.Bothdorsalandventralsupernumerarylimbswereofthesamehandednessasthelimbstumpandtheyweremirror-imagesoftheregeneratedevelopingdirectlyfromthetransplantedblastema.Following180°rotation,supernumerarylimbsaroseclosetothegraftjunctionatthosepositionswhereanterior-ventralandposterior-dorsallimbtissueswereincontact.Thesupernumerarylimbwhicharoseintheposterior-dorsalpositionwithrespecttothelimbstumpwasamirror-imageofthetransplant,andwasthereforeofoppositehandednesstobothtransplantandstump.Thesupernumerarylimbwhicharoseintheanterior-ventralpositionwasofthesamehandednessasbothtransplantandstump.Anewmodelofpatternregulationinepimorphicfieldswhichcanaccountfortheseresultsandwhichhasretrospectivevalueintheinterpretationofearlierexperimentsondevelopinglimbsisdiscussed.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
