Mouse cerebella were stained with Myo1d (green) and MBP (red) at P3, P7, and P13. A) Myo1d is expressed throughout the cerebellum in the Purkinje (asterisk) and, region of deep nuclei (open triangle). A′) The motor is absent from the molecular cell layer (bracket). A″) Myo1d is also present throughout the granule cell layer (arrow). B–B″) Upon the onset of myelination at day 7, Myo1d expression expands along axonal tracts (arrowhead). B′–B″) Myo1d is present in the Purkinje cell layer and has a restricted expression pattern in the granule cell layer. C–C″) At day 13, Myo1d expression is maintained in the Purkinje and granule cell layers, and is distinctly present along axonal tracts. Bar, 200 μm.