ELECTRON .^IICKDSCOPY 



Fig. 4. Renal amjdoidosis. Detail of amyloid 

 precipitate inside an endothelial cell. A system of 

 parallel fibrils are seen in the amyloid. 



~;4 ■ ''^: -t 



Ci/?i 



Fig. 5. Diabetic glomerulosclerosis. Diffuse 

 thickening of the capillary basement membrane 

 (Bm) and focal accumulation of foreign material 

 between the basement membrane and the endo- 

 thelial cell (End). 



ied seven patients with renal amyloidosis. 

 Clinical examination showed massive pro- 

 teinuria, decreased glomerular filtration and 

 a low filtration fraction. Electron microscopy 

 of renal biopsies showed changes similar to 

 those described by Geer et al. In early cases 



there was swelling and vacuolization of the 

 endothelial cells. The basement membrane 

 was thickened and folded but without visible 

 structure. In more severe or prolonged cases 

 a foreign substance accumulated between the 

 endothelial cells and the basement mem- 

 ])ranes. The epithelial cells were also altered 

 and finally completely desquamated and re- 

 placed by amyloid masses. Similar observa- 

 tions have been described by Movat (1959), 

 Putois (1959) and Meriel et al. (1960). In 

 severe cases very fine filaments were seen in 

 the newly formed substance in the basement 

 membranes and above all in the desquamated 

 epithelial cells. 



Diabetic Glomerulosclerosis. The glo- 

 merular lesions in diabetic glomerulosclero- 

 sis have been described by Irvine et al. 

 (1956); Bergstrand and Bucht (1957, 1959); 

 Dalgaard (1958b); Cossel et al. (1959); 

 Farquhar et al. (1959) ; and Hartman (1959). 

 The histologic alterations as viewed with the 

 electron microscope were very similar to 

 those of renal amyloidosis. The foreign 

 "hyaline" substance was accumulated be- 

 tween the endothelial cells and the glomeru- 

 lar capillary basement membranes which 

 were uniformly thickened. These changes 

 correspond to the "diffuse" type of glomeru- 

 losclerosis as observed by light microscopy. 

 The hyaline masses also bulged into the 

 vacuolated endothelial cell cytoplasm. The 

 endothelial cells were partly destroyed by the 

 large masses which obliterated the capillary 

 lumina. These changes correspond to the 

 "nodular" lesions, observed through the 

 light microscope. In the hyaline material 

 close to the endothelial cell membrane very 

 fine filaments could be demonstrated. There 

 was little damage to the epithelial cells in 

 early stages of the disease, and these changes, 

 which included a loss of foot process organi- 

 zation, were regarded by the authors as sec- 

 ondary to the lesions in the basement mem- 

 brane. 



Conclusions. The diseases which are as- 

 sociated with the nephrotic syndrome are by 

 many authors regarded as metabolic disor- 



212 



