Mitochondrial abnormalities in muscle from vitamin B12-deficient sheep

Skeletal and cardiac muscles from vitamin B12-deficient sheep were examined. Histochemical studies did not reveal any gross pathological changes in the muscle structure, but there was an abnormal distribution of the product of the NADH-diaphorase reaction. Electron microscopy revealed an abnormal distribution of mitochondria, changes in the number and arrangement of cristae within the mitochondria and the presence of inclusions. The possibility that alterations in mitochondrial morphology are early lesions attributable to metabolic changes in vitamin B12 deficiency is discussed.