Muscle fiber degeneration and necrosis in muscular dystrophy and other muscle diseases: cytochemical and immunocytochemical data.

Serial consecutive frozen sections from 164 muscle biopsy specimens were studied cytochemically. We localized calcium and albumin as endogenous markers of extracellular fluid penetration and C3 and C9 complement components as markers of muscle fiber necrosis. In both Duchenne dystrophy and congenital muscular dystrophy, a significant percentage of fibers were overloaded with calcium and penetrated by albumin. Most of these fibers appeared opaque with trichrome stain. C3 and C9 complement components appeared only in necrotic fibers, which invariably were also penetrated by albumin. These observations support previous findings that muscle fiber necrosis is linked to massive inflow of extracellular fluid and complement activation. In addition, in both Duchenne and congenital dystrophies, numerous nonnecrotic fibers are penetrated by calcium-rich extracellular fluid.