Ultrastructure of gastointestinal smooth muscle in ducks with a vitamin E-selenium deficiency.

The earliest ultrastructural lesions involving smooth muscle of duck duodenum and gizzard produced by a vitamin E-selenium deficiency were a degereration of sarcoplasmic reticulum and mitochondria. Lysosomes were not observed during these earliest alterations of deficient smooth muscle. Lipid droplets and mineral deposits were present in more severely degernerating smooth muscle that was being infiltrated by heterophils. In areas of necrotic smooth muscle, myoblasts were forming while macrophages, fibroblasts, and an occasional syncytial giant cell contained lipid droplets and surrounded coalesced mineral crystals. Endothelial cells of capillaries and stromal connective tissue were less severely affected with lesions developing after the earliest signs of smooth muscle degeneration. Neuroaxonal degeneration of nonmyelinated nerve fibers was not observed until after most of the smooth muscle had undergone either degeneration or necrosis. A possible explanation for the pathogenesis of the smooth muscle necrosis is discussed in light of the ultrastructural findings.