Ultrastructural studies of the myotendonous junction of selenium-deficient ducklings.

An ultrastructural study was made of the changes occurring within the gastrocnemius insertion of normal and selenium-deficient ducklings from 1 to 12 days of age. The cytologic characteristics of the fibroblasts, vessels, collagen, and muscle cells are described. Those exposed to the selenium deficiency showed major alterations of all components. The fibroblasts showed changes ranging from collapsed cisternae and degenerating mitochondria to rupture. The capillary endothelium was abnormal, as was the smooth muscle of arteriolar walls. The collagen sizes were altered, and the muscle cell termini showed major pathologic changes. The above alterations occurred within 4 days of exposure of the deficiency. The muscle cells of the body portion of the gastrocnemius showed no alterations until Day 8. The observations present evidence that indicates that connective-tissue-vascular abnormalities precede myopathic changes in nutritionally induced dystrophy. The significance of these findings is discussed with respect to the etiology of nutritionally induced dystrophy.