Figure 2. Microglial proliferation after CCI injury.

Confocal images show localization of proliferating microglial cells (Iba-1⁺, red, BrdU⁺, green) in the perilesional area of the cortex at 1, 3 and 7 dpi. At 1 dpi Iba1⁺ /BrdU⁺ cells have activated microglial morphology (A, inset in a). By 3 dpi proliferating amoeboid microglial cells showed hypertrophic cell body and shorter, thicker ramifications (B, inset in b). There is still significant proliferation of microglial cells at 7 dpi, with cells exhibiting a macrophage-like morphology (C, inset in c). In sham mice, proliferating microglia in cortical areas show a highly ramified phenotype, corresponding to a resting, non-activated state at 3 dpi (D, inset in d). Arrows indicate cells shown in high magnification in the corresponding panels. Scale bar=50 μm in (A, B, C and D) and 20 μm (a, b, c and d). (E) Quantification of Iba-1⁺/BrdU⁺ cells at different time points after CCI or sham injury (mean±S.E.M., n=3–6). *P<0.05, **P<0.01, by two-tailed Student's t test comparing sham and CCI at each time point.