FIG. 9.

Rounded fibers in FLNc-deficient mice. (A) Hematoxylin and eosin staining of facial muscles showing rounded fibers (arrows) among unaffected fibers in mutant mice. (B) ×40 and ×60 magnifications of the α-actinin staining in limb muscles from a homozygous mouse show expected striated staining in many fibers (panels G and H, arrowheads) as well as diffuse staining in rounded fibers (panel G, marked by a star). The specific fiber in this field is half disorganized, with areas of striation still retained (panels G and H, marked by arrows). (C) Electron micrographs of muscles from forelimbs of mutant mice. Most of the muscle fibers exhibit normal sarcomeres (top panels). The rounded fibers with centrally located nuclei show extensive thick and thin filament crossover and loss of distinct Z-lines (bottom panels).