Effects of the apical ectodermal ridge on growth of the versene-stripped chick limb bud☆☆☆

[摘要] 1.1.Thisinvestigationwasundertakentotestwhetherdeleteriouseffectsoftheexposureoflimb-budmesodermtoamnioticfluidduringectodermalhealingareasignificantfactorinthesuppressionoflimboutgrowthwhichoccursafterremovaloftheapicalectoderminthechickembryo.2.2.Isolatedlegbuds,strippedofectodermbyVersenetreatment,weregraftedtothestumpofahostwingbudinnormalanteroposteriorandproximodistalorientation.Thesegraftswerepoorlyvascularized,becamemassivelynecrotic,andfailedtodifferentiateterminallegparts.3.3.Similarlygraftedlegbudsweresuppliedwiththeapicalectodermalridgeofthehostwingbud,butwiththeirdorsalandventralsurfacesexposedasbefore.Thesewerevascularizedrapidly,showedlittleornonecrosis,anddifferentiatedtypicalpartsoftheshank,tarsometatarsus,anddigits.4.4.Itmaybeconcludedthat:(a)prolongedexposureofdenudedlimbmesoblasttotheamnioticmilieudoesnot,ofitself,causedegenerativechangeswhichsuppressterminaloutgrowthofthelimbbud;(b)theapicalectodermalridge,ormaterialintimatelyassociatedwithitandthesubjacentmesoblast,caninduceoutgrowthinlimb-budmesoderm.5.5.Theseresultsandtheconclusionsdrawntherefromarediscussedinthelightofrecentstudiesofectoderm-mesodermrelationshipsinthedevelopinglimbbud,particularlythosecarriedoutinthelaboratoriesofAmprino,Bell,Saunders,andZwilling.

[学科分类] 生物科学（综合）