Effect of aging on microglial proliferation and cell infiltration. Number of BrdU+
(A) and BrdU+/Iba1+
(B) cells in the peri-infarct area (cortex) at 7 and 14 days after MCAO in young and aged mice. The number of BrdU+ and BrdU+/Iba1+ cells (microglial/macrophages cells) was quantified on digitalized confocal images (see Methods). Representative images of Iba1+ cells in the ipsilesional peri-infarct hemispheres in young and aged mice. Scale bar = 50 μm (C). MCAO, middle cerebral artery occlusion.