A schematic representation of the possible origin of myogenic cells in regenerating skeletal muscle. Regenerated fibers (characterized by centrally located nuclei) are formed by fusion of myogenic cells (dotted red) that may derive from resident, activated satellite cells (orange) or from cells derived from the microvasculature, either as circulating cells (violet), or as endothelial cells (light blue) or pericytes (yellow) of the vessel wall. A green nucleus symbolizes the activation of a myogenic program.