Representative correlative light and electron microscopic images and pre-embedding immunoelectron microscopic images showing the ultrastructural characterization of reactive NG2 glia in the hippocampal CA1 region on day 14 after reperfusion. Confocal microscopic images of semithin sections double-labeled for NG2 and Iba1 (left panels of 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 boxed areas in right panels in A and C (left panels of B and D). Moreover, the boxed areas in the left panels in B and D are enlarged in the right panels of B and D, respectively. Note that reactive NG2 glia (NG2; shaded in green) have euchromatic nuclei (labelled as nu in the left panels of B and D) with prominent nucleoli (arrow in the left panel of B) and cytoplasm containing a well-developed rough endoplasmic reticulum. Cell nuclei are stained with DAPI. (E, F) Pre-embedding immunoelectron microscopic images of reactive NG2 glia in the stratum radiatum. The boxed areas in E are enlarged in F. Note that NG2 immunoreactivity, as indicated by highly electron-dense DAB grains, is localized along the plasma membrane of NG2 glia (shaded in green) and the adjacent extra-cellular matrix. Scale bars represent: 2 μm in A and C; 1 μm in the left panels in B, D, and E; and 0.1 μm in the right panels in B, D and F.