1. Morphological investigation of Purkinje cell dendrite and dendritic spine according to functional evolution in the rat cerebellum

The lobule of cerebellum is classified phylogenetically into archicerebellum, paleocerebellum and neocerebellum. The previous studies based on transmission electron microscopy reported the density of the synapses between parallel fiber varicosities and Purkinje cell dendritic spines is higher in neocerebellum than archicerebellum. The morphometric analysis of dendritic spines with high-voltage electron microscope was undertaken to reveal morphological diversity of the dendritic spine according to functional compartment of the cerebellum. Adult rat cerebella were dissected and stained according to a rapid Golgi protocol. Four-micrometer sections were observed with high voltage electron microscopy and some morphometric analyses were performed with Scion Image. The density, length, diameters of spine neck, area of spine and spine shape distribution were measured in the lobule II, VI and X in the vermal and paravermal regions. No significant differences in the density, length, and area of spine and spine shape distribution throughout the cerebellar lobules were observed. The diameters of dendritic spine neck showed moderate difference in the case of mushroom and branched-type spines. The diameters of dendritic spine in neocerebelum (VI) showed a tendency smaller than that of spine neck in the lobule II and X. The dendritic spine morphology of Purkinje cells did not show remarkable difference throughout the lobules. We need to do more works to explain the different results in this study from the previous reports.