Primary cultures of satellite cells were induced in differentiation. When myotubes formed, the cells were fixed and labeled with antibodies against titin and Trisk 49 (panels a, b and c), or IP3R and Trisk 32 (panels d, e and f). The nuclei were stained with TO-PRO 3 (blue labeling in panels c and f). Titin and Trisk 49 antibodies labeled only myotubes (aligned nuclei) and not myoblasts (isolated nuclei), and both presented a striated pattern. IP3R and Trisk 32 antibodies label the myotubes (multinucleated cells) and the myoblasts (isolated nuclei), with a diffuse punctuated pattern.