Fig. 2: Exercise increases neurogenesis in adult rats. (Ai–Aiii) Images of 42-day-old cells from a control animal (Ai) and an animal given free access to an exercise wheel (Aii). New neurons are shown in red, whereas mature granule cells are green, and astrocytes are blue. (Aiii) Confocal image of boxed area outlined in red from Ai. For new cells to be considered neurons, they must stain red (bromodeoxyuridine [BrdU], a marker of new cells) and green (Neuronal Nuclei [NeuN], a mature neuronal marker), but not blue (glial fibrillary acidic protein [GFAP], a marker of mature astrocytes). The cell at the centre of the white crosshairs is flipped 90° in both the x and y planes to ensure that the cell is co-labelled for both BrdU and NeuN. (B) Figure shows that exercise (black bars) increases the number of BrdU-positive cells in animals compared with controls (white bars), irrespective of the dose of BrdU administered to the animal (data adapted from Eadie et al, J Comp Neurol 2005;486:39-47⁴⁷).