Variability of neuropathologic lesions in experimental methylmercurial encephalopathy in primates

Acute and chronic intoxications of rhesus monkeys with methylmercury produced lesions in the central nervous system (CNS) with different distributions. Neuronal degeneration and astroglial proliferation predominated in the dentate nucleus, lateral geniculate nucleus, thalamus and pontine nuclei in 2 monkeys that received 2 mg/kg/day for 17 and 18 days, whereas pseudolaminar necrosis and astroglial proliferation were observed in the cerebral crotex, maximally in the calcarine and insular regions, in 4 monkeys that received 0.5 to 0.8 mg/kg/day for 3 to 8.5 months. Mercury concentrations in the CNS were much higher in the acutely intoxicated animals than in the chronically intoxicated animals, but the correlation between concentrations of mercury and the histologic destruction was not precise.