Transected myofibres may remain permanently divided in two parts

During regeneration of transected myofibres a scar is formed between their stumps. Myofibres restore their tendon-muscle-tendon continuity and contractile function by attaching to the scar with new myotendinous junctions. The scar contracts with time, and thereby the stumps are pulled close to each other. During early regeneration, myoblasts and myotubes can fuse with the surviving parts of the transected myofibres. However, it is not known whether it is possible that the opposite stumps could eventually fuse to reunite the divided parts of the transected fibres. In this study, we show in rat that even after 12 months the stumps remain attached to the separating scar by myotendinous junctions without showing definite fusion of the stumps. We conclude that transected myofibres probably remain permanently divided in two consecutive tendon-muscle-tendon units.