Reconstitution of the spinal cord after ablation in adult Triturus☆

[摘要] Afterablationof2–4mmofspinalcordinthepostbrachialregionofadultTriturusviridescensandT.pyrrhogaster,studieshavebeenmadeonthemechanicsofreconstitutionofthecordandthereturnoflocomotoryactivitiesposteriortotheablationlevel.Cinematographicrecords,aswellasdirectobservations,havebeenusedinstudiesonlocomotion.Theaveragetimeforappearanceofattemptstoswimwas76dayspost-ablation;successfulswimmingoccurredatanaverageof89days.NormalswimmingstrengthwasnevercompletelyregainedinadultTriturus,asitwasinearlierstudiesonlarvalAmbystoma.Reconstitutionofthespinalcordisinitiatedbyhealingateachtransectionsurface,followedshortlybydilationofthecentralcanaltoformanelongatedterminalvesicle.Numbersofnervefibersgrowingoutfromthewallofeachterminalvesicleultimatelyunitewiththewalloftheoppositevesicletoestablishnervefiberbridges.Inmanycases,perhapsinmost,fiberbridgesareorientedinadirectcourseacrosstheablationgap.Inotherinstances,oneormorenervefiberbridgesoccupyaberrentpositionswelloutsidethelimitsoftheablationgapandvertebralcanal.Regardlessoftheirnumberorpositions,nervefiberbridgeseventuallyformfunctionallongitudinaltractsofthereconstitutedwhitematterofthespinalcord.Studiesofserialsections,includingcountsoftotalcellnumbersandmitoticfiguresatvariouslevels,indicatethatrepopulationoftheablationgapbyneurons,andtheconsequentreconstitutionofthegraymatter,appearstobetheresultofbothcellmigrationandcellproliferation.Thetypesofmigratoryactivitieswhichappeartobeinvolvedarediscussed.

[学科分类] 生物科学（综合）