Fig. 1. Granule cell migration out of the EGL is delayed in Bdnf^–/– mice. (A) Dividing granule cells in P11 wild-type and Bdnf^–/– littermates were labeled by systemic injection of 50 mg/kg BrdU. Cerebellar tissue was then collected and processed for BrdU immunohistochemistry at the indicated times post-injection. Adjacent sections were stained with Cresyl Violet. EGL, external germinal layer; ML, molecular layer; PC, Purkinje cell layer; IGL, internal granule cell layer. Scale bar, 50 µm. (B) At 42 hours post-BrdU labeling, there is a significant reduction in the number of granule cells in the molecular layer and IGL in Bdnf^–/– mice. *P<0.005 by two-tailed t-test. (C) At 96 hours post-BrdU labeling, fewer granule cells have migrated into the IGL while more BrdU-positive cells remain in the EGL and molecular layer of Bdnf^–/– mice. The total number of labeled granule cells did not differ between genotypes. *P<0.005 by two-tailed t-test.