Fig. 1. Comparison of the number of BrdU-positive cells in adult and developing control and mutant brains. (A) The number of BrdU-positive cells in the cerebral cortex (Ctx), thalamus (Th) and cerebellum (Cb) of adult mutant brains (n=6) was not significantly different from those in adult control brains (n=6). The data plotted are mean±s.e.m. Cerebral cortex, P=0.42; thalamus, P=0.46; cerebellum, P=0.57. (B) The number of BrdU-positive cells in developing mutant brains (n=5) was significantly increased relative to those in controls (n=3). Cerebral cortex, P=0.001; thalamus, P=0.007. ^**P<0.01. (C) Sections from the P8 control cerebral cortex (a,c) and thalamus (e,g), and the P8 mutant cortex (b,d) and thalamus (f,h) were stained with an anti-BrdU antibody. In contrast to the control P8 brains, which have low proliferation, the mutant brains contain significantly more BrdU-positive cells. Scale bars: 100 µm.