Regenerated muscle fibers in Duchenne muscular dystrophy: a serial section study.

Muscle fibers from two boys with Duchenne muscular dystrophy and one normal boy were, for 6 mm, traced in serial sections. In normal muscle, we saw no branching or terminating fibers, and fiber diameters varied in different levels by +/- 5%. Dystrophic muscles showed signs of regeneration after segmental necrosis: multiple branchings, caliber variations, and short noninnervated fibers. In rats, muscle fibers regenerate without innervation but eventually they are replaced by fat cells. In Duchenne muscles, some regenerates lack innervation and possibly vanish as well; this may explain why regeneration finally fails.