Figure 2: Microgliosis indicated by Iba1 immunostaining in hippocampus at 2 wks and 4 wks after microlesion. Panels on the left ((a), (c), (e), and (g)) illustrate the microglial response on the unlesioned control side, and the panels on the right ((b), (d), (f), and (h)) are the corresponding lesioned sides. Panels (a), (b) = Iba1 immunostaining; (c), (d) = BrdU+ cells corresponding to sections (a) and (b), respectively. Panels (e), (f) are merged images of Iba1-BrdU signal 2 wks after lesion. Panels (g), (h) are merged images of Iba1-BrdU signals 4 wks after lesion. Insert box shows a merged confocal microscopic image of double-labeled Iba-1-BrdU. (i) Microgliosis assessed by image analysis of Iba1 signal. -axis = mean Iba1 signal area (as percent of hippocampal field at 20x magnification). Microglial signal was 16 times greater on the lesioned side than control at 2 wks (*). The microglial signal on the lesioned side declined significantly after 4 wks (**) but remained significantly elevated compared to the unlesioned side. (j) BrdU signal area was 3 times greater on the lesioned side at 2 wks and declined after 4 wks. (k) A number of Iba1+ cells were approximately 2.45 times greater on the lesioned hippocampus compared to the nonlesioned control at both 2 and 4 wks (*). Notice that microglia in the lesioned hippocampus are larger than on the control side, and therefore, the total Iba1 signal area is much greater than total number of cells. (l) A number of double-labeled microglia (Iba1/BrdU) were also greater on the lesioned side than controls at both 2 wks (*). Double-labeled microglia comprised ~36% of the total number of Iba1+ cells. Scale μm.