Abnormal sarcomere morphology Internally nucleated skeletal muscle fibers 2017-07-02T20:11:21Z An abnormally increased proportion of nuclei of sarcomeres with an internal localization. Individual muscle fibers are syncytia, formed by embryonic fusion of many myoblasts or later, myosatellite cells. Each muscle fiber contains many nuclei, peripherally positioned immediately adjacent to the sarcolemmal membrane. In healthy muscle only 3-5% of fibers contain nuclei that are located internally, within the cell, but many disease processes lead to internal nuclei. A normal muscle fiber contains many nuclei, peripherally positioned immediately adjacent to the sarcolemmal membrane. In healthy muscle only 3-5 percent of fibers contain nuclei that are located internally, within the cell, but many disease processes lead to internal nuclei. Internally nucleated skeletal muscle fibres