630 THE URINARY ORGANS. 



marked deformities of the organ, and to such minute changes as are in fact charac- 

 teristic of what we are wont to call chronic diffuse nephritis. 



The capillaries of the tufts may become partly or wholly obliterated by a gradual 

 thickening of their walls and an increase of the connective tissue between them, while 

 at the 'same time Bowman's capsule is thickened and contracts upon the altered tuft 

 (Fig. 390) with which it may unite so that the glomerulus may finally be represented 

 by a small, dense spheroidal mass of fibrous tissue (Fig. 39] ). 



The interstitial tissue of the kidney may be increased in patches, most often at first 

 near the glomeruli or along the interlobular veins. This tissue may at first be quite 

 cellular, resembling a collection of small spheroidal cells or larger polyhedral cells, 

 among which new fibrillar stroma may develop ; or there may be a more diffuse in- 

 crease of connective-tissue cells and stroma. As this new-formed fibrous tissue grows 

 less cellular it contracts, the tubules which it encloses are atrophied, the epithelium 

 may undergo fatty degeneration and peel off or become 

 flattened, casts may be present in the narrowed lumen 

 and the tubules may at last be represented by a small 

 cluster of flattened cells without distinct tubular structure, 

 or they may disappear altogether (Fig. 390). Such islets 

 or masses of new-formed fibrous tissue enclosing variously 

 altered and atrophied remnants of glomeruli and tubules 

 vary greatly in size and usually merge gradually into less 

 altered kidney tissue. When they are formed near the 

 surface of the kidney, the shrinkage of the fibrous tissue, 

 ^-^^ - _ which is continuous with the inner layers of the capsule, 



f^>4p<>& ma . v draw the surface inward, leaving between the irregu- 



lar depressions the areas of less altered, or otherwise al- 



FIG. 391. ATROPHIED GLOM- tered, kidney tissue somewhat projecting in irregular 

 ERUU-S IN CHRONIC NEPHRI- knobs or granules. Thus arise the granular surface and 

 the adhesion of the capsule which are frequent in some 

 The tuft is converted into a forms of persistent diffuse nephritis, 

 dense mass of fibrous tissue. In the partg of the ki( j ney j esg j nvo l ve d, or not at all 



involved in the production of new fibrous tissue, the tu- 

 bules may undergo marked alterations. Thus the epithelium may be swollen and 

 coarsely granular or fatty ; it may become necrotic so that the nucleus fails to stain ; 

 it may, when necrotic or degenerated, peel off or disintegrate so that the tubules may 

 be extensively denuded. On the other hand, the epithelium may remain in position 

 but be much thinner than normal, while the lumen is largely dilated. This may take 

 place by the blocking of the tubules below by desquamated cells or by compression 

 of new-formed interstitial tissue. The whole tubule, not merely the lumen, may be di- 

 lated and irregular in shape, with well-preserved or fatty or otherwise altered epithe- 

 lium. Casts of various forms may be present. 



CHRONIC DIFFUSE NEPHRITIS. 



General Considerations. We have seen that when the inflammatory 

 process in the kidneys, at first acute, is protracted, both the degenerative 

 and the productive lesions may become more marked and extensive. 

 Thus with a preponderance now of the interstitial alterations and again 

 of the degenerative or other changes in the parenchyma, the kidneys in 

 a condition of chronic diffuse nephritis may present a considerable va- 

 riety in gross as well as microscopical appearance. They are sometimes 

 larger than normal, as is often though not always the case when the par- 

 enchyma is more conspicuously involved ; or smaller, as is usual when 

 the interstitial lesions are widespread or advanced. 



