PATHOLOGY 



capillaries. They corresponded to the amy- 

 loid masses which were observed in the light 

 microscope. The endothelial cells were vacou- 

 lated and the number of perforations of the 

 cytoplasm (pores) was decreased. There was 

 also a proliferation of the endothelial cells. 

 The epithelial cells showed no damage other 

 than a focal loss of organization of foot proc- 

 esses similar to what has been observed in 

 lipide nephrosis. 



There were small nodular thickenings of 

 the basement membranes in the epithelial 

 cells from the proximal and distal tubules. 

 Similar material as described above was ob- 

 served in the interstitial tissue, but it could 

 not be demonstrated with certainty that this 

 was amyloid. The brush border of the proxi- 

 mal tubular epithelium was flattened with a 

 decreased number of cytoplasmic processes 

 and the basal infoldings of the cell mem- 

 branes were also diminished in number. In 

 the cytoplasm of the tubular epithelium were 

 droplets of fat and large opaque granules. 



Further observations on renal amyloidosis 

 in man have been published by Spiro 

 (1959a). This author has treated his sections 

 with PTA (phosphotungstic acid) for 24 

 hours after the routine preparation. In these 

 sections dense and thickened areas were 

 found in the glomerular capillary basement 

 membranes alternating with apparently 

 emptj^ spaces with a diameter of several 

 hundred AU. The author considered the lat- 

 ter to be large ''pores" in the basement 

 membranes and responsible for the abundant 

 proteinuria in his patients. We have not been 

 able to confirm these observations in our 

 laboratory; we do not think that it is possi- 

 ble to exclude that they are artifacts due to 

 the prolonged treatment with PTA. Spiro 

 also obsei-ved destruction of the epitheUal 

 cells and fine filaments in the amyloid 

 masses, similar to those described by Miller 

 and Bohle. In severe cases larger fibrils with 

 a striation similar to that of collagen were 

 observed. 



Bergstrand and Bucht (1959a) have stud- 





•jri--**- 



^^'^■^^::. 



c, 



4' 





1, 



:j 



Fig. 2. Nephrotic Syndrome. "Mixed type" 

 Nephrosis. Severe swelling and vacuolization of 

 the endothelial cell (End). Slight focal thickening 

 of the capillary basement membranes. Also 

 marked swelling of the epithelial cell (Ep) with 

 partial loss of foot process structure (Fp). 



I^J^,^ 



Fig. 3. Renal amyloidosis. Several capillary 

 lumina (Cap) with a thin covering of endothelium. 

 The amyloid masses are localized to the capillary 

 basement membranes and to the space between 

 them where remnants of destructed epithelial 

 cells (Ep) are seen. 



211 



