The fate of newly formed satellite cells during compensatory muscle hypertrophy.

Compensatory hypertrophy was induced in the rat extensor digitorum longus muscle by extirpation of the synergistic tibialis anterior. Injections of 3H-thymidine (2 muCi/g body weight) was given at 24, 48, and 72 h after the operation. In animals killed immediately after the last injection both satellite cell nuclei and true muscle nuclei were labeled, whereas in animals killed 4 weeks later only true muscle nuclei were labeled. The results are interpreted as indicating incorporation of newly formed satellite cells into the fibers during compensatory hypertrophy.