Evolution of cytoplasmic fibrillar bodies induced by lead in rat and mouse kidneys

Characteristic cytoplasmic and intranuclear fibrillar bodies were produced, within 24 hours, in epithelial cells of the proximal convoluted renal tubules of rats and mice by injecting a single dose of lead acetate either intraperitoneally (100 mug Pb/g) or into the heart (10 mug Pb/g). The frequency of cytoplasmic fibrillar bodies (CFB) rose during the first 4 days following injection of lead and diminished thereafter. Ten days after intracardiac injection of lead no CFB were found; 10 days after intraperitoneal injection, they were still present, though probably in diminished number. Disappearance of CFB may be related to autophagocytosis. Intranuclear fibrillar bodies did not disappear, perhaps because nuclei lack a lysosomal apparatus. Within the first 3 days after injection of lead, clusters or paracrystalline arrays of ferritin molecules were frequently situated in the immediate vicinity of CRB or abutted against CFB; after the third day, little or no ferritin was found near CFB. Intramuscular injection of iron-dextran complex (50 mg Fe/ml) 24 hours prior to intraperitoneal administration of lead did not increase incidence or size of ferritin clusters in the vicinity of CFB in rats. The presence of ferritin near CFB may have been an indirect consequence of inhibition, by lead, of synthesis of heme prosthetic groups.