Progressive Intercapillary Glomerulosclerosis in Aging and Irradiated Beagles

Specimens of tissue from the kidneys of 168 beagles entered in longevity experiments at the University of California at Davis were examined by light, electron, and fluorescence microscopy. At 10 to 12 months of age, these dogs had received a single exposure or fractionated whole-body exposures to X-rays in total doses of 100 R or 300 R. A progressive glomerular lesion was observed in aged, unirradiated control dogs which was similar histologically to the progressive intercapillary glomerulosclerosis (IGS) previously observed in aging rodents. IGS appeared earlier and was more advanced in the most heavily irradiated (300-R) dogs. A lesser increase in the severity of IGS was noted in dogs given 100 R in a single exposure or in two fractions of 50 R each. Ultrastructurally, basement membrane thickening, increased mesangial matrix, and electron-dense deposits on the inner surface of the basement membranes characterized the lesion. Gamma globulin (IgG) was demonstrated in the mesangium and basement membrane in...