Fig. 7. Bergmann glia scaffold defects lead to granule neuron migration defects. (A) Sagittal sections immunostained with BLBP (a) and counterstained with DAPI (a'). In Pten mutants (P7), severe Bergmann glia layering defect (b) coincides with major granule neuron accumulation within the ML (b'). Arrow indicates normal positioned Bergmann glial cell body; arrowhead pointed to ectopic Bergmann glial cell body. (B, a-c) Bergmann glia defects after adenovirus mediated Pten deletion were associated with increased granule neurons within the ML. HDA.Cre/YFP virus was injected into Pten^loxp/loxp;Rosa26^{floxed-Stop-lacZ} cerebella at P3 and the tissues were processed 8 days after injection. Bergmann glial scaffold defects were a direct consequence of viral CRE-mediated Pten deletion (B, a,b, area indicated by paired arrows) and coincides with granule neuron heterotopia in the ML (B, a-c; red boxed area for injected side; blue boxed area for uninjected control). Granule neurons accumulated within the ML were negative in X-gal staining (red boxed areas in B, a,c). EGL, external granule layer; ML, molecular layer; BG, Bergmann glia layer; IGL, internal granule layer. Scale bars: 50 µm.