Blebs in the mouse cerebellar granular layer as a sign of structural inhomogeneity. 2. Posterior lobe vermis.

When the adult mouse cerebellum is perfusion-fixed with 70% ethanol, paraffin-embedded, sectioned, and the sections are rehydrated, the granular layer wrinkles into an elaborate array of blebs. In the posterior lobe vermis these blebs are seen in both transverse and sagittal sections, are symmetrical about the midline, reproducible between neighboring sections and between individuals, and bear a constant relationship to the Purkinje cell bands as revealed by zebrin II immunocytochemistry. The data suggest that blebs represent individual cytoarchitectonic units and thus that the mouse cerebellum is subdivided into several thousand modules, each comprising >10(2) Purkinje cells and their associated interneurons and glial cells.