(A) X-gal staining of tibialis anterior (TA) muscle from mdx MymkLacZ/fl and mdx MymkLacZ/scKO mice, with cross-sectional area distribution of LacZ+ cells (n = 5–6). (B) X-gal staining of diaphragm with cross-sectional area distribution (n = 5–6). (C) smRNA-FISH for Mymk transcripts in quadriceps muscles of mdx MymkscKO mice and controls, with laminin immunofluorescence staining (n = 5). Quantification of Mymk+ cells per field with average cross-sectional area shown on right. Statistical analyses and data presentation: (A and B) Mann-Whitney U and unpaired t tests; *P < 0.05, **P <0.01, ***P < 0.001, and ****P < 0.0001; (C) unpaired t tests; **P <0.01. Data are represented as mean ± SD. Scale bars: 100 μm (A and B), 20 μm (C).