FIG. 3.

Regeneration of skeletal muscle is not impaired in M-cadherin null mutant mice. Hematoxylin- and eosin-stained sections of hind limb muscle from heterozygous and homozygous mutants were prepared at indicated times after injection with cardiotoxin (A). Blue staining indicates LacZ expression from the mutant M-cadherin locus that is particularly visible in homozygous mutants. Note the infiltration of the necrotic areas by mononucleated cells at day 2 and newly formed fibers with centrally located nuclei at day 10. Regeneration of damaged muscle appears similar in heterozygous and homozygous mutants. A Western blot of protein extracts from regenerating hind limb muscle indicates that components of adhesion junctions are equally upregulated in heterozygous and homozygous animals. Samples were taken at the indicated time points after cardiotoxin injection. Panel C illustrates the induction of muscle-specific transcription factors in regenerating hind limb muscle of homozygous and heterozygous M-cadherin mutants over 20 days following cardiotoxin injection. mRNA levels were determined by semiquantitative RT-PCR with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a control.