Centrally nucleated fibers (CNFs) are the myofibers which have nuclei in the center of cytoplasm, and are generally recognized as regenerated myofibers. They are commonly observed in the histopathology of the patients with several types of muscular dystrophies and their animal models. In the mdx mouse, an animal model of Duchenne muscular dystrophy, CNFs are more resistant than non-CNFs to mechanical stresses, as evidenced by the Evans blue infiltration. In relation to the population among muscles, CNFs are supposed to compensate the fragility of muscular tissue in muscular dystrophies and their animal models.