(A) 14 days running caused significantly increased proliferating cell number (indexed by Ki67 immunoreactivity) in the dentate gyrus of male C57Bl/6 J mice, no longer present after 28 days. (B) Marker for proliferation: fluorescent immunohistochemistry against Ki67 (red). (C) Both 14-days and 28-days of running increased survival (indexed by BrdU staining) in the dentate gyrus in these animals. (D) Representative photomicrograph showing a marker for survival: BrdU-immunoreactive cells in the dentate gyrus (red). (E) and (F) Running increases the number of new born neurons that reach maturation: 28-days running significantly increased the % of BrdU-labelled cells (red) that co-localised with calbindin (mature neuronal marker: green). (G) and (H) Both 14-days and 28-days running increased differentiation (indexed by DCX staining) of newly born cells into immature neurons in the dentate gyrus. (B + D) Scale bar = 50 μm (F) Scale bar = 20 μm (H) Scale bar = 70 μm Data represent means ± S.E.M. *p < 0.05, **p < 0.01, ***p < 0.001 vs. corresponding control.