Review Article

The Basis of Muscle Regeneration

Figure 3

Schematic diagram of time-dependent cellular response following cardiotoxin (CTX) injection. The relevant biological responses, activated after CTX injection, are indicated. A few hours after cardiotoxin treatment, neutrophils infiltrate between the necrotic fibers, and, by 24 hr after injection, the inflammatory response is characterized by neutrophil and macrophage infiltration. At this stage, the phagocytosis of necrotic myofibers is very active. During the second day after treatment, spindle-shaped mononucleated cells mixed with necrotic debris, leukocytes, and different classes of macrophages appear. New myofibers appear during the following day, and, by 7–10 days after injection, the overall architecture of the muscle is restored, although most regenerated myofibers are smaller and display centrally located myonuclei. The progressive maturation of regenerating myofibers occurs by 15 days.
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