CD68 and ischemic stroke: Compared with the young mice, the old mice had more CD68+ cells in the peri-infarct region at 1 day (old vs. young: 35.1±7.3% of total DAPI positive cells vs. 26.4±6%, p=0.0006), 3 days (old vs. young: 47.3±8.4% vs. 40.1±8.9%, p=0.006) and 14 days (old vs. young: 19.4±5.0% vs. 13.4±3.5%, p=0.032) after ischemic stroke (Fig. 3A).