Fig. 2. Morphological analysis of primary cultures of human satellite cells in normo- and simulated microgravity conditions. In normogravity conditions, samples derived from CTRL (a) and OA (b) patients were characterized by the presence of numerous myotubes (arrows) and rare satellite cells (asterisks); in OP patients (c), primary cultures were mainly formed by single satellite cells (asterisks) and rare myotubes (arrows). In simulated microgravity conditions, a significant increase in myotubes (arrows) in all experimental groups (d,e,f) was observed.