Fig. 3

Embryonic MyHC in regenerating muscle fibers. a Expression of embryonic myosin in regenerating rat skeletal muscle at various time periods after bupivacaine-induced injury. The progression of muscle regeneration from day 3 to day 14 after injury can be followed in serial sections stained with hematoxylin and eosin (upper panels) or immunostained for embryonic myosin (lower panels). Note the absence of embryonic myosin in the control muscle. Bar = 50 μm (modified from [65]). b Regenerating muscle fibers staining for embryonic myosin in human myopathies. Section of human muscle biopsy from a patient with polymyositis stained for MyHC-emb (red) and laminin (green). Note the large number of regenerating muscle fibers reactive for embryonic myosin. Bar = 50 μm (courtesy of Elena Pegoraro)