Ultrastructural alterations in skeletal muscle of ducklings fed selenium-vitamin E-deficient diet.

Newly-hatched ducklings were fed a selenium-vitamin E-deficient diet for 13 to 21 days. Ducklings were killed sequentially and the skeletal muscle alterations were studied by light and electron microscopy. An early alteration in skeletal muscle fibers was lysis of myofibrils, at first focal and later widespread. The sarcoplasm of damaged fibers appeared hyalinized by light microscopy. Degenerated skeletal muscle fibers with extensive lysis of myofibrils also had marked mitochondrial alterations, including swelling, formation of matrical densities, disruption of cristal membranes, and persistence of thick, dense, wavy, disrupted membranes. A sheath of external lamina persisted over degenerated segments of fibers which were invaded by macrophages that phagocytosed and removed the sarcoplasmic debris. Regeneration in damaged fibers was thought to proceed from thin subsarcolemmal satellite cells that survived the degenerative process. These satellite cells apparently developed into myoblasts, which fused to form myotubes that extended through the degenerated segments of fibers. Fibrillogenesis and sarcomerogenesis were apparent in myotubes. These structural alterations are discussed in terms of current knowledge of the combined biochemical role of selenium and vitamin E in maintaining cellular integrity.