Abstract
Four groups of 56 Sprague-Dawley SPF rats of both sexes were maintained on diets containing 0, 0.4, 2 or 10 ppm methylmercury chloride (MMC) for 130 weeks to examine the pathological changes in the chronic toxicity of this compound. Sixteen males and 12 females of the 10 ppm group were affected by the toxic peripheral sensory neuropathy characterized by loss of nerve cells in the spinal ganglion and nerve fiber degeneration in the spinal dorsal root, spinal dorsal funiculus and distal peripheral nerve. There were no histological changes in the cerebrum and cerebellum from the animals of any treated groups. Toxic changes in the renal proximal tubular epithelium were observed in the 2 and 10 ppm groups of either sex. Such changes were more prominent in the 10 ppm group, and were followed by subsequent interstitial fibrosis after 64 weeks. The animals with these severe renal lesions frequently showed hyperparathyroidism. In addition, there were significantly increased incidences of hepatic bile duct hyperplasia, splenic hemosiderosis and extramedullary hematopoiesis in males, and polyarteritis nodosa in females of the 10 ppm group. The tumor incidence was not altered by the feeding of MMC.
