Figure 6. Granule cell migration occurred normally in the α6fl/fl;nestin-Cre mice. (A) Dividing granule cells in P10 control and α6fl/fl;nestin-Cre littermates were labeled by systemic injection of BrdU. Cerebellar tissue was then collected and processed for BrdU immunohistochemistry at the indicated post-injection times. Twenty-four hours post-BrdU labeling, the granule migration had not yet begun. Forty-eight hours post-BrdU injection the BrdU-positive cells were migrating from the EGL, through the ML, to reach the IGL. Scale bar, 40 µm. (B) Laminar distribution of migrating granular cells in cerebellum from P12 control and α6fl/fl;nestin-Cre mice, 48 h after BrdU injection. Four sections were counted per animal (2 controls and 3 mutants). The percentage of BrdU-labeled cells in each layer was not significantly different in control compared with mutant mice. Error bars indicate SD. Scale bar, 50 μm. EGL, external granular layer; ML, molecular layer; IGL, internal granular layer.