Autometallographic mercury correlates with degenerative changes in dorsal root ganglia of rats intoxicated with organic mercury.

Organic mercury intoxication in rats produces degenerative changes in the dorsal root ganglia and dorsal nerve roots. In a previous study of rats treated with organic mercury (2 mg/kg ) for 19 days, significant losses of ganglion cells (especially A-cells) and myelinated axons were observed in dorsal nerve roots and there was qualitative evidence of glial cell proliferation and the formation of Nageotte bodies (1). In the present study, the autometallographic silver-enhancement technique, for tracing inorganic mercury bound to sulphide or selenide (AMG-Hg), was applied to tissue sections of dorsal root ganglia and dorsal nerve roots of the same rats used in the earlier study. Satellite cells and macrophages that surrounded ganglion cells and formed Nageotte bodies were heavily labelled by coarse deposits of AMG-Hg, while the labelling of ganglion cells was less pronounced. A-cells were consistently labelled, while B-cells were only occasionally labelled. In the dorsal nerve roots, only a few AMG-Hg deposits could be seen in macrophages. At the ultrastructural level, AMG-Hg was observed within lysosomes of target cells. It is concluded that AMG-Hg is primarily located in glial cells and that the pattern of deposition of AMG-Hg is the same as that for the morphological changes observed in rats intoxicated with organic mercury.