Autoradiographic study of the distribution of olivocerebellar connections during the involution of the multiple innervation of Purkinje cells by climbing fibers in the developing rat.

The distribution of olivocerebellar projections was studied in 6--13-day-old rats using an autoradiographic method, to determine whether the adult-type sagittal banding pattern of these projections was already settled. Clear sagittal-labeled bands were seen within the cerebellar cortex as already as 6 days when all Purkinje cells are multiinnervated by climbing fibers and in older animals, where most Purkinje cells are monoinnervated. These data suggest that the sagittal zonation of the olivocerebellar connections is already settled in early development.