Fig. 1. Nuclear shape of C2C12 myoblasts and myotubes. C2C12 myoblasts were cultured in the growth medium for 1 day, and myotubes were formed by culturing for 4 days in the differentiation medium. (A) Phase-contrast images (a,c,e) and corresponding bisbenzimide H33258-stained images (b,d,f) of myoblasts (a,b) and myotubes (c-f). Arrowheads indicate the smooth nuclei of residual myoblasts in the myotube culture (c,d). (B) Electron micrographs of myotube nuclei. Bar, 20 µm (A); 5 µm (B).