Evidence for polarizing zone in the limb buds of Xenopus laevis☆
[摘要] Totestforthepresenceofpolarizingmesoderminanamphibian,Xenopuslaevishindlimbbudtipswererotated180°ontheproximodistalaxisandreturnedtothestump.Supernumeraryoutgrowthswereinducedinthepreaxialstumpandpreaxialtiptissues,andthemostpostaxialdigitalwaysformednexttothegraftedpostaxialtissue.Theoccurrenceofpolarizedsupernumeraryoutgrowthsindicatedthattheposteriorlimbbordercontainedapolarizingzone.Whenthelimbtipwascutatvaryingknownlengthsfromthebodywall,rotated,andgraftedtothelimbstump,theincidenceoftwinningalongtheproximodistalaxispermittedinsightintothedistributionofthepolarizingzonealongtheposteriorborder.Thelocationofpolarizingtissueswasfoundtobesimilartothatinthechickwingbudatcomparablestages.Toconfirmtheposteriorborderstumpinfluenceontherotatedpreaxiallimbtiptissues,180°tiprotationsweremadeattheproximodistallevelwiththehighestincidenceoftwinning.Inthesecases,theadjacentstumpposteriorbordertissues(polarizingzone)wereremoved,leavingasubstantialamountofthedeeperpostaxialstumptissue,however.Thefrequencyoftwinningfromtiptissueswasgreatlyreducedintheselarvaecomparedtothosewithrotatedlimbtipsonintactstumps.Cytologicalexaminationofsupernumeraryoutgrowthsresultingfromgraftsoftwo-nucleolatetipsontoone-nucleolatestumpsconfirmedthepreaxialsourceofthesupernumeraryoutgrowths.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
