Micro-dystrophin expression levels result in reduced mdx pathology. Hematoxylin and Eosin (H&E) analysis revealed a reduction in centralized nuclei, a hallmark of DMD pathology. (A, C) H&E staining of rAAV6 and rAAV8 micro-dystrophin muscle sections, respectively (8 week time point). (B,D) Micro-dystrophin immunofluorescence detection in serial sections of rAAV6 and rAAV8 cohorts, respectively. Scale Bar, 25 μm. (E) Micro-dystrophin expression results in a 25% decrease in centralized nuclei. (F) Frequency distribution demonstrating micro-dystrophin expression results in a significant increase in type I, IIa, and IIb fiber diameter for rAAV6 and rAAV8.micro-dystrophin injected mdx mice compared to mdx controls. (n = 5–6 per group) (p < 0.0001 ANOVA analysis).