Figure 3. MBP immunohistochemistry in the hippocampus of young (A), adult (B), and aged (C) gerbils. In the dentate gyrus, the density of MBP immunoreactive fibers is decreased in all layers with age. In the CA2/3 and CA1 regions, the density of MBP immunoreactive fibers is significantly reduced only in the stratum radiatum (SR) with age. GCL, granular cell layer; MoL, molecular cell layer; PoL polymorphic layer; SL, stratum lucidum; SO, stratum oriens; SP, stratum pyramidale. Scale bars=400 (A-C), 50 (A1-C3) µm. D: The relative optical density (ROD) of MBP immunoreactive fibers in the hippocampal subregions (n=7 per group; ^*P<0.05, significantly different from the young group, ^†P<0.05, significantly different from the adult group). The bars indicate the means±SEM.