Proteins 41 



Cloudy Swelling and Hyaline Droplets 



Elsewhere one of us has marshalled evidence for regarding this 

 common variety of reversible cell injury as the outcome of upset of 

 water, salt and protein metabolism (Cameron, 1956) . The argu- 

 ment, so far as it concerns protein upset, is based on experiments 

 devised by Spector (1954) and by Oliver and his colleagues (1954). 

 In searching for the sources of the urinary protein in nephrosis, 

 Spector showed that homologous blood proteins labelled with 131 I 

 are taken up in increased amounts by the tubule cells of nephrotic 

 rats and stored in the mitochondria and microsomes. These proteins 

 had been filtered out in large amounts by the glomeruli and ex- 

 creted in considerable quantities in the urine. About four to ten 

 times as much protein as normal was found in the tubule cells 

 which means that these cells were storing protein vigorously. At 

 this time, they show the microscopical picture of cloudy swelling. 

 Under such circumstances cloudy swelling may well be the outcome 

 of "accelerated function leading to protein storage." We are re- 

 minded of the suggestion made long ago by Rudolf Virchow who 

 attributed the cloudy swelling in a kidney undergoing compensa- 

 tory hypertrophy after the loss of the other kidney to functional 

 over-activity. 



Oliver and his colleagues have followed the development of 

 granules and droplets in renal tubule cells of rats given rat or 

 foreign protein parenterally and in patients with proteinuria and 

 tubular damage. They, too, find that a close relationship exists be- 

 tween the formation of such granules and mitochondrial disturb- 

 ance. In cells in which droplets are forming, mitochondria become 

 shortened and thickened, eventually take on club-like forms and 

 are masked by the new droplets, all of which stain by specific mito- 

 chondrial methods. Oliver concludes that proteins passing through 

 the glomerular filter are in part absorbed by the epithelial cells of 

 the proximal convolutions without any apparent alteration of the 

 cytological pattern unless the absorptive capacity is overruled either 

 by the amount or nature of the protein or by disturbance of tubular 

 cell function. When the absorptive powers of the tubules are ex- 



