Figure 4.

Impaired muscle regeneration in Fst^+/− mice. A, Sections of gastrocnemius muscles of wild-type and Fst^+/− mice after cardiotoxin-induced injury. At 21 d after injury, note the centrally located nuclei characteristic of regenerating fibers in the wild-type injured muscle (see inset) and the significantly increased extent of fibrosis in the Fst^+/− muscle. At 4 d after injury, note the presence of neonatal myosin in both wild type and Fst^+/− muscle. B, Quantification of amount of fibrosis at 21 d after cardiotoxin-induced injury as assessed by measurement of percent fibrotic area relative to total injured area. H&E, Hematoxylin and eosin; wt, wild type.