Brain tissue sections from 6 and 24 month old Fisher 344 rats were stained for nuclear stain DAPI (blue) and either MnSOD (green) or the endothelial cell specific marker VWF (red). Quantitative comparison of MnSOD expression between vessels derived from 6 month and 24 month old animals is shown in bar graph. Data are mean ± SD (n = 6). ×20. ***p < 0.001 vs. 6 months.