622 



THE URIXARY ORGANS. 



FIG. 383. GLYCOGEN DEGENERATION OF THE EPITHELIUM OF 

 THE KIDNEY IN DIABETES. 



niellitus. It is usually most marked in the cells of Henle's locps (Fig. 

 383). 



Calcification may occur in chronic inflammatory lesions or in old in- 

 farctions ; in the iutertnbular tissue of the medulla in the aged, or in 

 casts in the collecting tubes. 



INFLAMMATION. 

 General Considerations. 



Many of the alterations in the kidney which are commonly considered inflammatory 

 are in fact degenerative, and these degenerative changes are often so important and so 



conspicuous in the lesions as to 

 fairly dominate the gross and 

 microscopic appearances. The 

 processes in the kidneys which 

 may be properly considered in- 

 flammatory are either exudative 

 or productive, so that the appar- 

 ently complex series of kidney 

 changes which are grouped under 

 the name nephritis, or Bright's 

 disease, are really phases of exu- 

 dative or productive inflammation, 

 or both, associated with degener- 

 ative processes. 



Whether the kidneys be 



large or small, Avhite or red or mottled, smooth or rough ; whether the disease be acute 

 or chronic, it is always these comparatively simple processes, varying in extent, in 

 duration, in intensity, and in relative predominance, which are to be taken into the ac- 

 count in the study of inflammation of this organ. 



There are perhaps no lesions whose classification has seemed beset with such diffi- 

 culties as those of the kidneys. This is largely due to a failure to realize that the vari- 

 ous phases of inflammation and degeneration do not stand apart as independent proc- 

 esses or lesions, but are closely associated and often merge. It is difficult, perhaps 

 impossible, to make a classification which shall meet the requirements of the clinic, 

 the limitations of urinary tests, and at the same time accord with the revelations of the 

 autopsy and the microscope. 



One of the difficulties in framing a classification of kidney lesions is that there are 

 many and serious abnormalities in the function of the kidney which do not find expres- 

 sion in such structural changes as we can at present recognize. Our knowledge of such 

 of the minute structural lesions in the renal epithelium as are not manifested by altera- 

 tions in the size and form and organic integrity of the cell is, in fact, very meagre. 

 So that the attempt to classify inflammatory lesions of the kidney upon both clinical 

 and morphological data often leads to conjecture or confusion, frequently to both. 

 Considering the scope of this book and our present purpose, it seems wiser to set forth 

 here as concisely as possible the essential character of the lesions in acute and in chronic 

 phases of inflammation and degeneration in the kidney based upon morphological rather 

 than upon clinical data. 



It is convenient to divide the acute inflammatory processes of the 

 kidneys into two forms, Siippurative Nephritis and Acute Diffuse Nephritis. 



SUPPURATIVE NEPHRITIS. 



Suppurative inflammation of the kidney may follow injury with local 

 infection. It is, however, most often due to the presence of bacteria, 



