Fig. 3. Myofiber-specific OSKM induction promotes the activation and proliferation of satellite cells.

a Schematic representation of the experimental design. b Immunostaining of Pax7 and BrdU in TA muscle sections. Scale bars = 10 µm. c Quantification of the percentage of SCs with BrdU signals. Error bars represent mean + SD of five mice. d Immunostaining of Pax7 and MyoD in TA muscle sections. Pax7⁺ cells are indicated by arrows. Scale bars = 50 µm. Representative regions are shown at higher magnification with Scale bars = 10 µm. e Quantification of Pax7⁺ cells per field. Error bars represent mean + SD of five mice. f Quantification of the percentage of Pax7⁺MyoD⁻, Pax7⁺MyoD⁺, and Pax7⁻MyoD⁺ cells. Error bars represent mean + SD of five mice. g Illustration of the design for myofibers analysis. h Immunostaining of Pax7 and MyoD in single myofibers. Scale bars = 10 µm. i Quantification of Pax7⁺ cells per myofiber. n = 31 Cre− myofibers and 35 Cre+ myofibers, respectively. Error bars represent mean + SD. j Quantification of the percentage of Pax7⁺MyoD⁻, Pax7⁺MyoD⁺, and Pax7⁻MyoD⁺ cells in single myofibers. Error bars represent mean + SD of four Cre⁻ EDL muscles and 6 Cre⁺ EDL muscles. k Immunostaining of Pax7 and MyoD in single myofibers after culture for 3 days. Scale bars = 50 µm. l Quantification of cell clusters per myofiber. n = 28 Cre− myofibers and 30 Cre+ myofibers, respectively. Error bars represent mean + SD. m Quantification of Pax7⁺MyoD⁺ myoblasts per cluster. n = 76 cell clusters on Cre− myofibers and 128 cell clusters on Cre+ myofibers. Error bars represent mean + SD. A two-sided unpaired Student’s t-test was performed.