70 



tubule nearest the glomerules, appear in tlie urine, because they 

 are too large to pass through the narrow tubules) . The third and 

 largest are those developing in the straight collecting tubules. 

 It is believed a prognostic value may be attached to the size of 

 the casts as well as to their number. Casts from the narrow 

 tubules indicate a mild attack; from the convoluted tubules a 

 severe form, especially in the cortex of the kidney; from the 

 collecting tubules, with the other forms also present, a serious 

 condition of general renal inflammation or unfavorable prognosis. 

 The identity of casts may generally be determined by their uni- 

 form width. They are usually longer than they are broad, and 

 have one well-rounded extremity and well defined borders. 



True casts 

 are of six va- 

 rieties ; hya- 

 line, epitheli- 

 al, blood, 

 granular, fat- 

 ty and waxy 

 easts. In a 

 general way 

 the first three 

 varieties are 

 found in an 

 acute form of 

 n ep h r i t is. 

 During the 

 first few 

 weeks of the 

 inflammation 

 the last three 

 varieties are 

 not encoun- 

 tered. If the 

 acute condition passes into a subacute, then the granular variety 

 appears, at first in small number, then in larger, with, usually, 

 a considerable number of the hyaline and epithelial casts. Fatty 

 and waxy casts are always secondary products, and as a rule 

 not found until a nephritis has existed for some time. 



Hyaline casts are colorless, pale, more or less transparent 



Fig. 25. Granular Casts. (Greene). 



