Collapsed myofibers are degenerative cells with a disorganized cytoskeleton. (A) Representative photomicrographs of BF muscle sections showing different levels of actin organization. Level 0 corresponds to organized actin similar to normal EBD− myofibers, level I corresponds to actin disorganization (loss of periodicity and partial fragmentation), and level II corresponds to advanced fragmentation and/or loss of staining. Arrows indicate EBD+ myofibers, and asterisks indicate intact myofibers. Arrowheads indicate the loss of phalloidin staining (level II). (B) Scatter dot plot quantifying the relative density of MyoD+ cells in terms of actin disorganization. These results were obtained from four sections per muscle of BF (n = 3 muscles). (C) Representative images of BF tissue sections showing α-actinin impairment in damaged myofibers compared to intact myofibers. BF sections were stained with anti-α-actinin (green). Nuclei and MPCs were stained with DAPI and anti-MyoD, respectively. The asterisks and arrow indicate normal and impaired α-actinin patterns, respectively. *P < 0.05, **P < 0.01. All results are expressed as means ± SEM.