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Trans-filter propagation of apical ectoderm maintenance factor in the chick embryo wing bud☆☆☆
[摘要] Theexperimentsreportedhereweredesignedtoanalyzetransmissionofthepostulated“apicalectodermmaintenancefactor”fromthepostaxialportionofthewing-budstumpintopreaxialtissueofthereorientedwing-budapex.Inembryosofstages20–23,theapicalzoneoftherightwingbudwassevered,reversed(apdv)for5–24hours,andthenrestoredtonormalorientation.Apexesreversedfor12hoursormoredevelopedvaryingdegreesofexcessdigitationpreaxially,rangingfromanextraDigitIItoacompletemirror-twinhand.Extensivemirror-twinduplicationsalsoformedfrompreaxialtissueswithhighfrequency(75%)whentheapicalzonewaspermanentlyreversedwiththinMilliporefilterof0.8μporesizeinterposedbetweenthepostaxialportionofthewing-budstumpandtheapex.Fewerandlesscompleteduplicationsoccurredwithfiltershavingporesizesof0.45μor0.05μ,andnonewerefoundwhenanonporousMylarfilmwasused.Theresultsoftheseexperimentsarecompatiblewiththethesisthatthepostaxialportionofthewing-budstumpisthesourceof“apicalectodermmaintenancefactor”whichisrequisitetothemaintenanceoftheapicalridgeofectodermwhichinducesterminallimboutgrowth.Itissuggestedthatactivityofthefactormayinvolvestructuralmaterialwhichisapartofthegroundsubstancebutisrathercloselyassociatedwithcellswhichproduceit.Maintenanceoftheridgemaybearesponsetothisorderedenvironmentortosomeotherfactorwhosefreediffusionisguidedorrestrictedbythisenvironment.
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[效力级别]  [学科分类] 生物科学(综合)
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