(C) Quantification of VP (visual pruning) index (fluorescence intensity of pyramidal axons after vs. before the branch point). In WT animals after the pruning period, only a minor part of axons descends towards the pyramidal tract (WT: P9 0.65±0.09, adults 0.17±0.04, p=0.006). However, in crmp2-/- mice, corticospinal axons are still largely present, and their VP indexes are not significantly different between adult and P9 stages (crmp2-/-: P9 0.54±0.18, adults 0.62±0.27, p=0.24). Mean ± SD, **p<0.01, 2-way ANOVA with Bonferroni's multiple comparisons test. P9: n=3 pups/genotype, adults: n=5 mice/genotype) 