412 DISEASES OF THE URINARY ORGANS. 



tubule ; they may also result from the dilatation of Bowman's 

 capsules, and are often filled with a colloid material. Hya- 

 line and granular casts may be found within the tubules. At 

 an early stage of the inflammatory process the interstitial 

 tissue may be quite cellular, but the longer the duration of the 

 affection the more fibrous and the greater the increase in the 

 stroma ; from its contraction results the granular appearance 

 of the surface. The walls of the bloodvessels are almost 

 invariably thickened by an obliterating endarteritis 



Associated with these lesions in chronic interstitial nephritis 

 are nearly always a general arterio-sclerosis and a hypertro- 

 phied heart. 



DEGENERATIONS. 



Parenchymatous degeneration, or cloudy swelling of the kid- 

 neys, occurs in the course of diphtheria, scarlet fever, cholera, 

 and other infectious diseases ; and in poisoning from phospho- 

 rus, arsenic, and mercury. There is no sharp line of demarca- 

 tion between this condition and acute parenchymatous nephri- 

 tis, in which it is liable to terminate, the changes varying with 

 the virulence of the poison. The kidney is enlarged, rounded, 

 and soft in consistency. On section, the cortex is thicker than 

 normal, and pale or yellowish in appearance. 



Microscopically, the principal changes are noted in the 

 tubules of the cortex. The tubular epithelium is granular 

 and swollen ; the lumen of the tubule almost entirely oblit- 

 erated, often appearing as little more than a stellate fissure. 

 The cell outline is indistinct and its nucleus obscured. 



Fatty degeneration very frequently follows cloudy swelling ; 

 it often occurs also in the course of long-continued wasting 

 diseases, as cancer, tuberculosis, diabetes, and pernicious 

 anemia. The kidney is pale and extremely flabby, and 

 often smaller than normal ; on section the cortex is found to 

 be of normal thickness, and of a diffuse yellowish or mottled, 

 and greasy appearance. 



Microscopically, the convoluted tubules are especially af- 

 fected ; the cells are swollen, and near their bases are droplets 

 of fat of various size. 



Amyloid degeneration of the kidneys occurs in tuberculosis. 



