简介：BACKGROUND:Thecorticospinaltractisthecorestructureofcerebralcontrolofextremitymovementandplasticity,whichareprerequisitesformovementrehabilitationafterbraininjury.Themeasurementandassessmentofplasticitychangeswithinthecorticospinaltracthasbecomeoneofthekeygoalsinthisfield.OBJECTIVE:Toexploretheeffectsofbiotinylateddextranamine(BDA)asaneuraltracerintheratcorticospinaltractandthepossibilitiesofassessingplasticitywithinthecorticospinaltract.DESIGN:Anobservationalexperiment.SETTING:DepartmentofAcupunctureofChineseMedicalCollege,ChongqingMedicalUniversity,DepartmentofNeurology,theSecondAffiliatedHospital,ChongqingMedicalUniversity.MATERIALS:EighteenmaleadultSpragueDawley(SD)ratsofcleangrade,weighing200-250g,wereprovidedbytheexperimentalanimalcenterofChongqingMedicalUniversity.Theanimalproceduresinthisstudywereinaccordancewiththeanimalethicsstandards.BDAwasprovidedbyVectorLaboratoriesCompany(USA,catalogueSp-1140;serialnumberR0721).METHODS:ThisexperimentwasperformedintheLaboratoryofChongqingMedicalUniversitybetweenSeptemberandDecember2006.AdultSDratswereusedintheexperimentand15%BDAwasinjectedslowlywithamini-syringethroughtworound(3mmdiameter)holesintotheleftsensoryandmotorcortex.Thecenterofoneholewaslocated3mmanteriorfromtheanteriorfontaneland1.5mmleftofthemidline;thesecondholewaslocated1.5mmposteriorfromtheanteriorfontaneland4mmleftofthemidline.Threeinjectionsweremadeateachholeatthreedifferentlevels:1.4,1.2,and1mmventralfromthesurfaceoftheflatskull.After14days,thebrainsandspinalcordswereremovedandfrozen.SectionswerecutonacryostatandBDAtransportationabsorbedbyaxonswasobservedunderafluorescencemicroscope.MAINOUTCOMEMEASURES:AxonalabsorptionandtransportationofBDAwasobservedunderfluorescencemicroscope.RESULTS:EighteenS