The relationship of the zone of polarizing activity to supernumerary limb formation (twinning) in the chick wing bud☆

[摘要] Theroleofthepolarizingzonemesodermindevelopmentofsupernumerarydistalwingpartsafter180°rotationofthewingtipwasinvestigated.Postaxialmesodermwithandwithoutpolarizingtissuewasrepositionedpreaxiallyinthewingbudandduplicationsoccurredonlywhenpolarizingzonetissuewasincluded.Whenthepolarizingzonewasremovedandthedistaltipofthewingreoriented,noduplicationresulted.Similarlywhenthepolarizingzonewasremoved,thedistaltipreorientedandpostaxial,nonpolarizingmesodermintroducedtorestorethetissuemassofthestump,notwinningoccurred.However,withthedistalaspectreorientedonastumpfromwhichpostaxial,nonpolarizingmesodermwasremoved,twinningoccurredin92.9%ofthecases.Further,whenthepolarizingzonewasremoved,thedistalaspectreorientedandasmallpieceofpolarizingtissuereturned,twinningresultedin93.5%ofthecases.Theseresultsindicatethatpolarizingzonetissueisrequiredforthetwinningthatresultsafter180°rotationofthewingtip.

[学科分类] 生物科学（综合）