High-resolution identification of mercury in particles in mouse kidney after acute lethal exposure

Contamination of the food chain by mercury is a major concern of Public Health of our day. Kidney and nervous system are the major targets of mercury toxicity in mammals. We show here that the detailed subcellular in vivo topography of microparticles of mercury in tissues can be achieved by scanning electron microscopy (SEM) coupled with X-ray elemental microanalysis (XRM). SEM-XRM offered the fine topography of mercury in the kidney of BALB/c mice that were submitted to an intraperitoneal lethal injection of mercuric chloride (HgCl2). All of the renal mercury was seen inside blood vessels located in both cortex and medulla of the mouse kidney. This blood-born mercury was organised in spheroid particles of less than 50 nm in diameter (31.4 +/- 14.1 nm). They were seen attached either to aggregates of plasma proteins or to the surface of blood cells. No evidence of internalisation of mercury by blood, endothelial or kidney cells was found. The average kidney density of mercury microspheres was 1920 +/- 1320 particles per mm2. We propose SEM-XRM as an elective approach to further investigations, at the subcellular level, on the quantitative dynamics of mercury particles in the tissues.