CASTS. 



405 



erous tubules at the site of their formation, in nearly all 

 inflammations of the kidneys, and are but rarely present in 

 normal urine. 



The method of their formation is not perfectly understood 

 some probably by a species of secretion from the tubular 

 epithelium, and others by coagulation of serous exudations 

 into the tubules. 



In size they vary according to the part of the kidney in 

 which they are formed, measuring from 0.01 to 0.05 milli- 



FIG. 187. 



Granular casts (Musser). 



metre in diameter, and one-tenth to a millimetre and more 

 in length. Several varieties are distinguished. 



Hyaline casts are homogeneous, transparent, and colorless. 

 They are found in the urine from simply congested kidneys, 

 and in transient albuminuria ; often, moreover, in chronic 

 parenchymatous and interstitial nephritis. 



Granular casts are composed of a granular material re- 

 sulting from the breaking down of the epithelial cells of the 

 tubules. They are found especially in the urine from chronic- 

 ally inflamed kidneys. 



