Fig. 3.

Satellite cell contribution to tibialis anterior muscle plateaus between 8 and 12 weeks of age. a–d Images of TA muscle sections from mice that were harvested 2 weeks after the final tamoxifen injection show the percentages of tdTomato expressing myofibers decrease with age. Images display DAPI (blue), laminin (green), and tdTomato (red). Numbers in the 12-week image c illustrate tdTomato scoring metric. e Quantification of tdTomato-expressing myofibers in TA muscle sections by tdTomato expression level. +++ myofibers express high levels of tdTomato (1 in a), + myofibers clearly express tdTomato (2 in a), +/− myofibers have very low levels of tdTomato and are scored as negative (3 in a), and – myofibers do not express tdTomato at observable levels (4 in a). f Quantification showing the percentages of myofibers that express tdTomato (+ or +++) in TA muscle sections. g Quantification showing the percentages of tdTomato-expressing TA myofibers by location within the muscle. Scale bar is 50 μm. ****P < 0.0001. Mean ± standard error of the mean is plotted. Significance was determined by Student’s t test. Three to six biological replicates were analyzed per time point