Degenerative changes in the neonatal kidney following in-utero exposure to methylmercury

Pregnant Sprague—Dawley rats were injected with 4.0 mg Hg/kg body weight of methylmercuric chloride on the 8th day of pregnancy. Tissue samples from the kidneys of the offspring were obtained for electron microscopic examination. Degenerative changes in the epithelial cells of the proximal convoluted tubules (PCT) including accumulation of lysosomes, enlargement of the apical vacuoles, cytoplasmic vacuolation, and extrusion of large cellular casts into the tubular lumen were observed. Flattening of the basal infolding was found in some PCT epithelial cells. Deposition of basal filaments in these cells were also observed. Extrusion and embedding the spherical microparticles into the basement membranes of the PCT was also a prominent finding. No degenerative changes were seen in the distal tubules. However, degeneration of the Bowman's capsule of the glomeruli, fusion of the epithelial foot-processes, and detachment of the glomerular epithelial cells from their basement membranes could be observed occasionally.