PATHOLOGY 



no changes in the proximal tubules. In the Electron microscopic investigations of the 

 collecting ducts the mitochondria were en- excretion of radioactive mercury compounds 

 larged or destroyed. Ten days after potas- through the kidneys of rats have been made 

 slum had been administered 4^he mitochon- by Bergstrand et al. (1959). Mercury was 

 dria had regained a normal appearance. An demonstrated in the proximal tubular cells as 

 increased number of macrobodies and lipoid accumulations of very small and dark parti- 

 droplets was observ^ed in the tubular epi- cles inside large bodies similar to the "sider- 

 thelium of animals with cholin deficiency osomes" described by Richter. The presence 

 (Ash worth, 1959a, b). of mercury in the cytoplasm could not be 

 The effect on the tubular epithelium of demonstrated by the electron microscope, 

 heavy metals has been studied by several After homogenization of the kidneys and 

 authors, Dempsey and Wislocki (1955) stud- centrifugation at high speed, a very high ac- 

 ied the site of accumulation of silver in the tivity could be demonstrated in the micro- 

 tissues by giving a solution of silver nitrate some fraction which contained only the 

 in the drinking water to mice, rats and guinea smallest cell organelles, such as RNA-gran- 

 pigs for 6 to 12 months. The silver was ules, but no traces of mitochondria or "sider- 

 mainly located in the basement membranes osomes." Thus it is very probable that 

 of the glomerular capillaries and the tubular mercury was also present in the cytoplasm as 

 epithelium. In the epithelial cells of the prox- was demonstrated with iron by Richter. The 

 imal tubules silver could be demonstrated amounts of mercury were low and there was 

 inside mitochondria which had retained their no destruction of the tubular cells, 

 original structure and were easily identifi- Bencosme et al. (1959) have studied the 

 able. The metal appeared as very dense and effect of uranyl nitrate on the kidneys of 



o 



small particles w^ith a size of about 20-30 AU rats with the electron microscope. Extensive 



or as larger aggregates with a diameter of damage to the epithelial cells was observed 



one or several microns. Similar observations in the proximal tubules. The intercellular 



on rats have been made by van Breemen et al. spaces were widened, forming large cisternes 



(1956) and by Olcott and Richter (1958). probably containing resorbed tubular fluid. 



Richter (1957) gave repeated injections of No deposits of the metal were observed in the 



hemoglobin intraperitoneally to rats. Hemo- epithelial cells. The author concludes that 



siderin could be demonstrated in the proxi- the passage of fluid through the tubular walls 



mal tubular epithelium. Electron microscopy takes place mainly through the intercellular 



revealed large opaque bodies in the cells spaces, 

 containing numerous very dense particles 



with a mean diameter of 55 AU. Similar par- Conclusions on the Morphological Basis 



tides could be demonstrated in the cyto- "^ Glomerular Filtration 



plasm without apparent connections to any Electron microscopy of normal glomeruli 



cell organelles. The author named the large from man and animals has failed to reveal 



bodies "siderosomes" and considered them the structures in the capillary walls which 



to be derivatives of mitochondria. The small are necessary for the filtration process. Sev- 



particles corresponded in size to the iron eral attempts have been made to elucidate 



miscelles of purified ferritin, and the author the problem through a comparison of clinical 



concluded that ferritin is probably a com- data from patients with impaired renal 



ponent of hemosiderin. Similar iron-contain- function to the corresponding morphological 



ing bodies have been described under the changes of the capillary wall as revealed by 



name of cytosomes in other organs and in the electron microscope, 



macrophages (Lindner, 1958; Miller, 1959). Hall (1957) has concluded from studies on 



215 



