Fig. 4. Reduction in cell proliferation of TN-C-null mice. Proliferating cells were identified by BrdU uptake in vivo at ages from P0 to P17 in the SVZ of wild-type (WT) and TN-C-null (-/-) animals with the original genetic background described by Saga et al. (Saga et al., 1992), and from P2 to P10 in the SVZ, the cortex, the striatum and the corpus callosum of heterozygous (+/-) and homozygous TN-C-null (-/-) littermates with a C57Bl6J/CBA background. (A) The reduction in BrdU-positive cells in the TN-C null animals, as described in the text; note that for some values the error bars are too small to see at this scale (Student’s t test: *P<0.05, **P<0.01, ***P<0.001). (B) A schematic representation of a frontal section of the anterior part of the mouse brain with the boxed area showing the region of the SVZ in which BrdU-positive cells were counted. (C) The extensive BrdU labelling at P10 in the dorsolateral part of the SVZ of heterozygous animals. (D) lacZ expression in the SVZ, derived from the transgene in the TN-C-null mice, in the region shown in C,E (boxed area). (E) BrdU labelling of the dorsolateral part of the SVZ in homozygous TN-C-null littermates of those shown in C; note the reduction in labelling. V, ventricle. Scale bars: 400 µm in D; 100 µm in C,E.