Figure 4.

Transmission electron microscopy analysis of muscle stem cells. TEM analysis was performed to identify satellite cells according to their ultrastructural characteristics. In OA muscle biopsies we found several satellite cells generally placed between normal and degenerated fibers. In satellite cells syncytium (a) (arrow) we observed de novo production of sarcomeric structure (arrows) (10.000x and 50.000x) ((b)-(c)). TEM analysis of muscle biopsies from OP patients showed numerous degeneration areas (arrows) (2.500x and 5.000x) ((d)-(e)). Rare satellite cells syncytia (arrow) with obvious mark of degeneration, such as nuclear anomalies and vacuolations, we found in OP patients (5.000x) (f).