Alterations of the renal papilla during mercuric chloride-induced acute tubular necrosis

Marked morphologic changes were seen in all structural elements of the renal papilla during mercuric chloride-induced acute tubular necrosis. Expect for the descriptions of increased numbers of leukocytes within the medullary vasa recta, papillary changes have not been described previously. The techniques used in this study included light microscopy, scanning electron microscopy, and transmission electron microscopy. The renal interstitial cells developed an extremely irregular contour and were penetrated by large irregular cavelike structures. A marked decrease occurred in the size and number of the cytoplasmic lipid droplets in these cells. The volume of the Golgi area, and of the rough and smooth endoplasmic reticulum increased. The morphologic changes in the renal interstitial cells were indicative of increased activity rather than of cellular injury. This is of insterest because several investigators have postulated that the interstitial cells are the site of renal prostaglandin synthesis Incrreased prostaglandin synthesis and release have been proposed to play a role in the redistribution of renal blood flow seen during acute renal failure.

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.

Some effects of methyl mercury salts on the rabbit nervous system

Young adult rabbits have been given methyl mercury salts by subcutaneous injections or by gastric intubation. After 3 daily doses of 7.5 mg/kg by the 8th day moderate to severe ataxia developed, and after 4 doses, severe ataxia. Some of these latter animals might die. This species, therefore, seems to be about twice as sensitive to the neurotoxic properties of methyl mercury salts as the laboratory rat. With the light microscope extensive degenerative changes were seen in primary sensory ganglion cells, in both Purkinje and granule cells of the cerebellum, and in certain cells in several regions of the forebrain. The earliest changes became visible microscopically about the fourth day after commencing dosing, and reached a maximum of severity from the 7th to 10th day. The pattern of neuronal damage more closely resembled that found in the cat and in man than that seen in the rat. No evidence of changes vascular permeability was detected.

Cardiac and aortic lesions in chronic experimental poisoning with mercury vapors

The nature of the toxic influence of mercury and its effect on the cardio-vascular system are not well understood. In chronic poisoning with metallic mercury and its compounds, circulatory disorders have been observed in patients. The problem whether metallic mercury damages the endocardium and myocardium directly or indirectly through vascular changes or vegetative system stimulation remains unsolved. A study was undertaken in which a group of experimental rabbits was exposed to the chronic action of mercury vapors by inhalation and compared with a control group. Before the experiment and towards its end, ECG were taken and 24-hr urinary excretion of mercury was determined in both groups. After 3 months the animals were autopsied, and fragments of myocardium, papillary muscles, endocardium and ascending aorta were taken for histopathologic investigation. In the poisoned animals, the ECG tracings showed bradycardia. Morphologic lesions had the character of thrombosis in small and medium-caliber blood vessels, necrotic foci, thickening of the endocardium of the papillary muscles and perivalvular region and endothelial proliferation with inflammatory foci. The results indicate that, besides influencing the vegetative system, mercury vapor damages the endocardium directly and produces vascular lesions resulting in myocardial changes.

Alkylmercurial encephalopathy in the monkey (Saimiri sciureus and Macaca arctoides): a histopathologic and autoradiographic study

Histopathologic and autoradiographic studies were performed on monkeys of the genera Saimiri and Macaca after acute and chronic oral exposure to several dosage regimens of methylmercuric chloride (MeHg). Neuropathologic changes were primarily cortical, although subcortical lesions also were observed. Autoradiographic localization of 203-Hg was greatest within glial cells (particularly Nissl-pump astrocytes, subependymal glia and Bergmann's glia) and mast cells. High levels of label within normal appearing large neurons (particularly those within Gasserian and dorsal root ganglia) indicate a lower susceptibility of these neurons to the toxic effects of MeHg. Blood and brain levels of mercury correlated well with the degree of neuropathologic change, but individual variations in susceptibility to intoxication also existed.