Ultrastructural alterations in gizzard smooth muscle of selenium-vitamin-E-deficient ducklings.

Lesions of gizzard smooth muscle were studied by light and electron microscopy in newly hatched ducklings fed a selenium-vitamin-E-deficient diet for 13-21 days. Histopathologic alterations included initial hyaline change in damaged smooth-muscle cells, subsequent mineralization of sarcoplasmic debris in necrotic smooth-muscle cells, macrophagic invasion and phagocytosis of sarcoplasmic debris, and eventual fibroblastic proliferation and scarring of damaged areas in the gizzard wall. Ultrastructurally, mild damage in smooth-muscle cells was manifested by altered mitochondria with matrical densities and disrupted membranes and dilated elements of sarcoplasmic reticulum. In smooth-muscle cells with severe injury, the alterations of mitochondria and sarcoplasmic reticulum were accompanied by myofibrillar lysis and disruption of plasma membranes and external laminae. Expanding zones of mineralization of sarcoplasmic debris in necrotic smooth muscle cells were present at dense masses of lysed myofilaments that surrounded mineralized and disrupted mitochondria. Numerous macrophages infiltrated the areas of necrosis of smooth muscle and phagocytosed sarcoplasmic debris.