Skeletal muscle pathology in LmnaH222P/H222Pmice. (A) Representative micrographs of hematoxylin and eosin-stained sections of quadriceps, diaphragm, and tibialis anterior muscles from 20-week-old male LmnaH222P/H222P mice (Lmna H222P). Similar sections from wild-type mice (Lmna WT) are shown for comparison. Scale bar = 50 mm. Arrows indicate internalized nuclei. To the right of each pair of micrographs, quantitative analyses of muscle fiber diameter (Feret’s diameter) are shown for wild-type (circles, sold line) and LmnaH222P/H222P mice (squares, dashed line). Values are means ± SEM for n = 3 mice per group; **P <0.005, ***P <0.0005. (B) Bar graphs showing percentages of fibers in specified muscle groups with internalized nuclei. Values shown are means ± SEM for between 500 and 1,000 nuclei analyzed in tissue samples 3 per group; *P <0.05, **P <0.005, n.s. not significant.