Fig. 3. Histopathology of Dp116/mdx^4cv transgenic muscle is more severe than that of mdx^4cv. Hematoxylin and eosin stained sections from the diaphragm muscle at 4 weeks of age and diaphragm, quadriceps, and soleus muscles at 12 weeks age are shown for C57Bl/6, mdx^4cv, and Dp116/mdx^4cv mice. Widespread necrosis of muscle fibers and mononuclear cell infiltrates are more prominent in the diaphragm and soleus muscles of Dp116/mdx^4cv transgenic mice at all ages compared with mdx^4cv. The quadriceps muscles from Dp116/mdx^cv and mdx^4cv mice were not noticeably different at 12 weeks. Immunofluorescence staining of serial sections of 12 week soleus muscles with anti-CD11b antibody demonstrates infiltration of inflammatory cells in mdx^4cv and transgenic/mdx^4cv muscles. Inflammation in the transgenic/mdx^4cv soleus muscle was widespread and diffuse, in contrast to the focal pattern in mdx^4cv soleus muscle. Bars, 100 µm.