Acute reactions with collagen production in renal glomeruli of rats as studied electron microscopically.


 Striking glomerular changes arc seen electron microscopically in rat kidneys after acute uranyl nitrate poisoning. More interesting than the several glomerular epithelial cell reactions to this injury, perhaps, is the development of the nodular 
 centrolobular lesion containing collagen fibers. 
 The glomerular epithelial cell changes include loss of foot processes, the appearance of dense deposits in foot processes or in the larger portions of cytoplasm which replace lost foot processes, hyaline droplets, other cytoplasmic bodies with varying internal membranes and granules, myelin figures, and cytoplasmic vacuoles. The functional significances of these changes and of the observed proteinuria, polyuria, and oliguria arc discussed. 
 The nodular centrolobular lesion was identified with a trichrome stain after embedding in methacrylate. As seen with the electron microscope it consists of several components lying between the central dense layer of the basement membrane 
 and endothelial cells. Separately distinguished components include intercapillary cells and their processes lying in intimate contact with extracellular (a) small dense granules 30 m1i in diameter, (b) large bodies 400 ma in diameter, vaguely forming rough cords, and (C) collagen fibers, randomly oriented and appearing within four days after injection of uranium. The intercapillary cells, often containing clear vacuoles with very dense and thick osmiophilic walls, may later prove to be endothelial cells but their intimate association with collagen fibers raises other alternatives. 
 
 As part of a systematic investigation of reactions in the ultrastructure of the kidney I. under physiologic and pathologic conditions, glomerular changes in rat kidneys during acute uranium poisoning have been studied by electron microscopy. Some other aspects of this investigation are also being reported (2, 3, 27).