The spatial organization of the mouse cerebellum into transverse zones and parasagittal stripes is reflected during the temporal progression of Purkinje cell death in the Lurcher mutant mouse (+/Lc). Neurodegeneration in the +/Lc mutant is apparent by the second postnatal week and is initially seen in all four transverse zones: the anterior (lobules I-V), central (lobules VI, VII), posterior (lobules VIII, dorsal IX), and nodular (ventral lobule IX and lobule X) zone. However, from postnatal day (P)25-P36, Purkinje cell loss proceeds more rapidly in the anterior zone, followed by the posterior and central zones, and is significantly delayed in the nodular zone. Coronal sections through the +/Lc cerebellum reveal that surviving Purkinje cells are restricted to the paraflocculus/flocculus and the nodular zone and could be detected as late as P146 (approximately 5 months). Within this region, the pattern of preferentially surviving calbindin-immunoreactive Purkinje cells reflects the expression of the constitutively expressed small heat shock protein HSP25 in the wild-type cerebellum. Although the role of constitutively expressed HSP25 in the wild-type cerebellum is not clear, it appears to play a neuroprotective role in the flocculonodular region of the +/Lc mutant cerebellum as the percentage of surviving Purkinje cells that are HSP25-immunopositive significantly increases over time.