| Abstract: | The cerebellum of the meander tail mutant mouse (mea/mea) is characterized by a relatively normal cytoarchitecture posteriorly with an abrupt transition to an anterior region in which there is abnormal foliation, agranularity, and Purkinje cell (PC) ectopia. This study presents the results of a qualitative and quantitative analysis of the PC in the mea/mea cerebellum. Developmental and morphological analyses reveal that the PC in the anterior region of the mea/mea cerebellum do not form a monolayer during the first week of postnatal development as they do in the wild type mouse. In the adult mea/mea, the dendrites of these ectopic cells are atrophic and disoriented. Quantitative studies in adult animals reveal that while the total number of PC is normal, the number of PC in the affected anterior region of the mea/mea cerebellum is greater than the number of PC in the anterior lobe, as classically defined by the primary fissure, of the normal animal. These data suggest that 1) the developmental morphology of the PC in the anterior region is abnormal, probably due to the lack of granule cells at early postnatal times; 2) the total number of PC in the cerebellum is normal, and 3) the defect is not restricted to the anterior lobe but involves a portion of the posterior lobe. The latter supports the notion that the mutant gene affects a unique developmental compartment in the cerebellum which does not coincide with the classic adult boundary, the primary fissure, between the anterior and posterior lobes. © 1996 Wiley-Liss, Inc. |
