Representative correlative light and electron microscopic images showing the ultrastructural characterization of resting and reactive NG2 glia in the hippocampal CA1 region. (A~D) Ultrastructure of NG2 glia in the pyramidal cell layer (PCL; A, B) and stratum radiatum (SR; C, D) in the CA1 hippocampus of sham-operated rats. Confocal microscopic images of semi-thin sections double-labeled for NG2 and Iba1 (left panels in A and C), images of confocal microscopic data overlaid onto the corresponding electron microscopic images (right panels in A and C), and the corresponding transmission electron microscopic images obtained from the same fields (left panels in B and D). The boxed areas in the left panels in B and D are enlarged in the right panels in B and D, respectively. Note that resting NG2 glia (shaded in green) in both layers have nuclei (nu) containing clustered chromatin, as well as scanty cytoplasm with few cytoplasmic organelles. (E~H) Ultrastructure of NG2 glia in the pyramidal cell layer (E, F) and the stratum radiatum (G, H) of ischemic rats at 3 days after reperfusion. Confocal microscopic images of semi-thin sections double-labeled for NG2 and Iba1 (left panels in E and G), images of confocal microscopic data overlaid onto the corresponding electron microscopic images (right panels in E and G), and the corresponding transmission electron microscopic images obtained from the same field (left panels in F and H, right panel in F). The boxed areas in the left panels in F and H are enlarged in the middle panel in F and the right panel in H, respectively. Notably, reactive NG2 glia (shaded in green) in the two examined layers have abundant rough endoplasmic reticulum and well-developed Golgi complexes. Cell nuclei are stained with DAPI. Scale bars represent 1 μm in A, C, E, G and the left panels in B, D, F, and H; 0.2 μm in the right panels in B, D, and H; and 0.1 μm in the middle and right panels in F.