764 



THE URINARY TRACT. 



The changes just described I was also enabled to see in the tubules of 

 another kidney, in the immediate neighborhood of small forming abscesses. 

 The circumstance that at times formations resembling nuclei are imbedded in 

 the cast is comprehensible, if we consider that the epithelial body may disap- 

 pear in the formation of the cast and the nucleus be left unchanged. Granular 

 casts are probably formations in which the epithelia have not yet undergone 

 such extensive changes as are requisite for the production of perfect hyaline 

 casts. Yellow casts are the result of the imbibition of the coloring matter of 

 the blood by the coagulum. Waxy, shining casts may be secondarily changed 

 products, the same as casts which are abundantly provided with fat-granules. 

 (See Fig. 345.) 



Not infrequently we observe combinations of catarrhal and croupous 

 nephritis, in which cases abundant desquamated epithelium is to be found in 

 the urine, but only a few hyaline casts. As, according to the above advanced 



FIG. 345. ACUTE. CROUPOUS NEPHRITIS IN THE NEIGHBORHOOD 

 OF A FORMING ABSCESS. 



C, tubule in transverse section, filled by a hyaline cast ; JS, tubular epithelia at the 

 beginning of proliferation; I, interstitial connective tissue crowded with inflammatory 

 corpuscles ; their rows probably corresponding with former blood-vessels. Magnified 1000 

 diameters. 



views, all forms of inflammation present only gradual differences, further- 

 more, even in diffuse nephritis, the kidney is never uniformly diseased 

 throughout its substance, but rather in foci, I believe that the presence of a 

 few casts, especially in the narrow tubules, when accompanied by catarrhal 

 changes in the epithelium of the convoluted tubules, is easily explained. The 

 most numerous blood-vessels run in groups along with the narrow tubules. 

 Here, accordingly, the inflammation can easily reach a higher grade than 

 in the region of the tufts and of the convoluted tubules. This also explains 

 why, after healing of croupous nephritis, irregular cicatricial retractions appear 

 on the surface, between which there are coarse elevations of a comparatively 

 little changed kidney tissue. After croupous nephritis the contraction is 

 always irregular and deep, not leading to a granulation of the surface. The 

 large, fatty and amyloid kidneys are probably always products of secondary 

 changes after an original, acute, croupous nephritis. 



