Inductive and axial properties of prospective wing-bud mesoderm in the chick embryo☆

[摘要] Prospectivewing-budmesoderm,strippedofectodermmechanicallythroughtheuseofglassneedles,orchemicallybymeansofEDTAortrypsin,wasobtainedfromdonorembryosofstages11through21.Graftsweremadeinbothhomopleural(aaddandapdv)andheteropleural(aadvandapdd)combinationstotherightflankofhostembryosofthesamerangeofstages.Flankectodermfromthehosthealedoverthegraftinafewhoursand,incombinationsbetweendonorsandhostsintherangeofstages12through17,thecompositeformed,withhighfrequency,alimbbudcappedbyanapicalectodermalridge,andthendevelopedintoasupernumerarywinginwhichallproximodistallevelswererepresented.Wheneithermemberofthecombinationwasolderthanstage17,onlyincompletelimbs,ifany,wereformed.Regardlessoftheirorientationonthehost,thesupernumerarylimbsalwaysshowedtheaxialcharacteristicsappropriatetotheirsideoforigin.Supernumerarywingsfailedtoformifthegraftswereinsertedintoaspacetunneledbetweenflankectodermanditsunderlyingmesoderm.Ifthecoveringectodermweredeliberatelytornandforcedtohealoverthegraft,however,anectodermalridgeformedandasupernumerarylimbdeveloped.Itisconcluded,therefore,that:(1)thewing-budmesoderm,appropriatelycombinedwithflankectoderm,hasthepropertyofmorphologicalandaxialself-differentiationbystage12;(2)theapicalectodermalridgeisinducedinflankectodermbyprospectivewing-budmesoderm;(3)thisinductivepowerisrestrictedtoprospectivewing-budmesodermfromdonorsofstages12through17;(4)theresponsecompetenceislimitedtoflankectodermthathashealedoverthemesoderm;and(5)thiscompetenceislostbytheendofstage17.

[学科分类] 生物科学（综合）