Characterization of NG2 glia in the hippocampal CA1 region of rats at days 3, 7, 14, and 28 following transient forebrain ischemia using double-labeling for NG2 and Iba1. (A~C) Lower- (A) and higher- (B, C) magnification views of the CA1 hippocampus 3 days after reperfusion. The boxed areas of the pyramidal cell layer (PCL) and stratum radiatum (SR) are enlarged in B and C, respectively. The numbers of NG2 glia (NG2⁺/Iba1⁻ cells) appear to increase in both the pyramidal cell layer and the stratum radiatum, whereas NG2-positive microglia/macrophages are preferentially localized to the pyramidal cell layer. Notably, NG2 glia in the pyramidal cell layer (arrowhead in B) have fewer and thicker processes than those in the stratum radiatum (arrowhead in C). (D~F) Lower- (D) and higher- (E, F) magnification views of the CA1 hippocampus 7 days after reperfusion showing that prominent NG2 and Iba1 expression appears in both the pyramidal cell layer and the stratum radiatum. Note that NG2 glia in the stratum radiatum (arrowhead in F) exhibit more numerous and complex branching processes compared to those in the pyramidal cell layer (arrowhead in E). (G~I) Lower- (G) and higher- (H, I) magnification views of the CA1 hippocampus 14 days after reperfusion. Immunoreactivities for NG2 and Iba1 are still prominent in both the pyramidal cell layer and the stratum radiatum. Note that NG2 glia in the pyramidal cell layer (arrowhead in H) have fewer and thicker processes compared to those in the stratum radiatum (arrowhead in I). (J~L) Lower- (J) and higher- (K, L) magnification views of the CA1 hippocampus 28 days after reperfusion, showing that immunoreactivity for NG2 is still observed in the pyramidal cell layer and the stratum radiatum, whereas Iba1 appears to be preferentially localized to the pyramidal cell layer. Note that NG2 glia in the pyramidal cell layer (arrowhead in K) have thick and short processes, while NG2 glia in the stratum radiatum (arrowhead in L) have numerous complex branching processes. Cell nuclei are stained with DAPI. Scale bars represent: 20 μm in A, D, G and J; 10 μm in B, C, E, F, H, I, K and L.