Figure 4

Myofiber branching increases with normal aging in wild-type mice. (A) In both gastrocnemius (GA) and extensor digitorum longus (EDL) muscles, myofiber branching increased with age in wild-type mice. (B) The majority of the branched myofibers from aged muscles contained only one branch. Data for GA and EDL muscles are pooled. (C) No significant differences were observed in branch types between GA and EDL muscles of aged mice. (D) The percentage of split branches increased with age in GA muscles. In all graphs, the adult mice were 2 to 6 months, and aged mice were 20 to 21 months old. In (A) and (C), 96 to 596 myofibers were analyzed per age and data are mean ± SEM of 4 to 31 mice. *P < 0.05. Data in (B) represent 21 to 46 branched myofibers from pooled GA and EDL muscles per age expressed as means of 10 to 35 mice. Data in (D) represent 18 to 31 branched myofibers from GA muscles expressed as mean ± SEM of 6 to 18 mice.