The development and growth of muscular fibers of striated skeletal muscle

Based on literature date and on their own experiences, the authors present the morphology, development and growth of the striated muscle, and the role of giant and splitting muscle fibers, and the mechanism of muscle splitting. The muscle develops from the myotom, the myoblasts become coherent myotubules, which then differentiate into muscle fibers. The longitudinal growth of the muscle fibers can take place through the elevation of the number of the sarcomeres or through their prolongation; however the exact mechanism of the morphological and structural changes in the skeletal muscle and myofibrils in the postnatal period is not clearly understood. Recent literature data suggests that postnatal growth of muscle can take place through the splitting of the giant muscle fibers. The presence and splitting of the giant muscle fibers seems to be related to the pathologic metabolism of the muscle, but their presence was detected also in normal muscles. The histological grading system, developed by the authors that provides an opportunity to define the stages (G1-G4) of split muscle fibers may be useful in the future also in the veterinary practice.