Fig. 1

Double Chromogen Staining of NDUFS4 and VDAC1. (a-d) Representative images of neurons from POLG tissue staining positive for NDUFS4, MRC complex I, characterized by a brown-stained cytoplasm, or negative for NDUFS4, exhibiting a magenta-stained cytoplasm. The magenta staining corresponds to VDAC1, a marker of mitochondrial mass, while the DAB brown chromogen indicates the presence of mitochondrial respiratory complex proteins (in this case, NDUFS4). Figures are from(a) prefrontal cortex, (b) occipital cortex (c) cerebellum, and (d) CA4 region of the hippocampus. Scale bars: 50 μm (e) Bland–Altman plot comparing measurements between Observer 1 (O1) and Observer 2 (O2). The x-axis represents the mean of the measurements from both observers, while the y-axis shows the difference between them