label: Internally nucleated skeletal muscle fibers
label_lc: internally nucleated skeletal muscle fibers
description: "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."