Limb outgrowth in the chick embryo induced by dissociated and reaggregated cells of the apical ectodermal ridge☆
[摘要] Mesodermalcoresofthestage19chicklegbudwerecappedwithanintactapicalectodermalridge(AER)orwithstripscutfromcentrifugalpelletsformedfromPronase-dissociatedAERs.Theywerethencoveredwithembryonicback-skinectodermandgrownasgraftstothesomiteregionofahostembryo.Controlmesodermswerecappedwithcentrifugalaggregatesofnonridgelimbectodermorsimilarlytreatedback-skinectoderm,withethanol-killedAERsorwithnoectodermalcellsotherthantheenvelopingback-skinectoderm.Controlswerevascularizedslowlyandatypicallyandshowedlittleoutgrowth,formingonlyproximalskeletalstructures.RecombinantsequippedwithAERcellswerevascularizedmorefullyandpromptlyandbeganvigorousgrowthafterbriefdelay,forminglegswithallskeletalsegmentsrepresented,includingclaw-tippedtoes.Thelatterwerearrangedinanteroposteriorordercorrespondingtotheoriginalpolarityofthemesoderm.HistologicalsectionsofrecombinantsmadewithcytologicallydistinctivequailAERsrevealthatthecapofridgecells,whetherinitiallyintactorreaggregatedbeneaththeback-skinenvelope,undergoaperiodofreorganization,formingatypicalAERattheapexofthechimericappendageafter48hr.Meanwhilevigorousgrowthoftherecombinantcontinues.TheseresultsshowthattheAERcancooperatewithnonlimbectoderminpromotingthemorphogenesisofsuccessivelymoredistallevelsofthelimbskeleton.TheyalsoshowthatdissociatedridgecellscanreorganizeatypicalAERattheapexofthelimbmesoblast,meanwhileexercisingtheirinductiveeffectonit.
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[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
