Figure 4.

A, Double-immunofluorescence staining for PAX3/7 (green) and PCNA (red) from young (upper panels), old (middle panels), and old+testosterone-treated gastrocnemius muscles (lower panels) shows colocalization of PAX3/7 and PCNA (yellow). Scale bar, 50 μm. Panels B and C, Quantitation of the numbers of PCNA (B)- and myogenin-positive (Panel C) shows a significant increase in the number of these cells in aged muscles after testosterone treatment. Values are mean ± sem. Means with unlike letters are significantly (P < 0.05) different.