Enlarged vesicles in WR motor neurons. Quantification of vesicle diameters in WT, WR and SOD1 (G93A) tg motor neurons, judged by electron microscopy (WT, WR) and by immunohistochemistry (WT, WR, SOD1 (G93A)tg). Cross-sectional vesicle diameters were determined by ImageJ analysis (see M&M section) for 100 different APP-positive motor neurons in serial cervical spinal cord sections (n = 10 per genotype, 10 sections per individual) from WR, WT, and SOD1 (G93A) tg mice, respectively. Values are given as mean values ± SD. P-values < 0.01 between WT, WR, and SOD1(G93A) were considered significant with *, p < 0.01 and **, p < 0.001.