muscle cell myotube Multinucleated muscle cell formed by several fusion events between fusion competent myoblasts and one founder cell. The size of a myotube is correlated to the number of fusion competent cells that fuse with a founder cell or developing myotube. muscle fiber CL:0002372 In contrast to vertebrates, in Drosophila embryos and larva, each muscle is a single myotube (Maqbool and Jagla, 2007). myofibril FBbt:00005812 fly_anatomy.ontology myofiber