The cerebellar nucleocortical projections in the rat. A retrograde labelling study using horseradish peroxidase...

Following injections of wheat germ agglutinin-horseradish peroxidase conjugate in the cerebellar cortex of adult rats, retrograde cellular labelling was of two kinds within the cerebellar deep nuclei: (i) of high intensity, in those nuclear regions that also showed anterograde terminal labelling; this topographically arranged nucleocortical projection has therefore been called 'reciprocal'. 'Reciprocal' projections to zone A, to the zones C1 and C2, and to zone D come from the nucleus medialis, the interposed nuclear complex, and the nucleus lateralis, respectively; (ii) of low intensity, in nuclear areas surrounding the previous ones. No nucleocortical projections could be evidenced to either B or the C3 zones.