REN. 



259 



also some increase of vascularity. As the 

 disease advances, the cortical portion gradually 

 wastes, and the entire organ becomes con- 

 tracted, firm, and granular, the medullary 

 cones remaining comparatively unaffected even 

 in the most advanced stages ; simultaneously 

 with the diminution in the size of the kidney 

 there is a decrease of vascularity. These 

 changes occur very gradually ; the disease 

 having a duration in most cases of many 

 months, and in some even of several years. 



On placing thin sections of the kidney 

 under the microscope, some of the tubes are 

 seen to be in precisely the same condition as 

 in a case of acute desquamative nephritis : 

 they are filled and rendered opaque by an 

 accumulation within them of nucleated cells, 

 differing in no essential respect from the normal 

 epithelium of the kidney. This increase in 

 the number, and this slight alteration in the 

 character of the epithelial cells are the result 

 of the elimination by the kidney of mal-assi- 

 milated products, which are being continually 

 developed in gouty and intemperate subjects, 

 and which are not normal constituents of the 

 renal secretion. 



There would evidently be a certain limit to 

 the number of cells which can be formed in any 

 one of the uriniferous tubes ; for although some 

 of the cells escape with the liquid part of the 

 secretion, and so may be seen in the urine, 

 as in a case of acute desquamative nephritis, 

 yet in many of the tubes the cells become so 

 closely packed that the further formation of 

 cells becomes impossible, and the process of 

 cell-formation, and consequently of secretion 

 within these tubes, is arrested. The cells, 

 thus formed and filling up the tube, gradually 

 decay and becomes more or less disintegrated. 

 While these changes are occurring in the tubes, 

 the Malpighian bodies frequently continue 

 quite healthy, their capsules for the most part 

 transparent, and the vessels in their interior 

 perfect. From these vessels water, with some 

 albumen and coagulable matter, is continually 

 being poured into the tubes ; and, as a conse- 

 quence of this, the disintegrated epithelial 

 cells are washed out by the current of liquid 

 flowing through the tubes, so that, on ex- 



Fig. 170. 



Casts of the urinary tubes, composed of fibrinous 

 matter and disintegrated epithelium from the urine, 

 in a case of chronic desquamative nephritis. Mag- 

 nified 200 diameters. Med. Chir. Trans, vol. xxx. 



amining the sedimentary portion of the urine, 

 we find in it cylindrical moulds of the urinary 

 tubes, composed of epithelium in different 

 degrees of disintegration, and rendered co- 

 herent by the fibrinous matter which coagu- 

 lates amongst its particles, (fig. 170.) 



There is reason to believe that when the pro- 

 cess of cell-development and of secretion have 

 once been arrested by a tube becoming filled 

 with its accumulated contents, the tube never 

 recovers its lining of normal epithelial cells ; 

 but when the disintegrated epithelium has 

 been washed away from the interior of the 

 tube, the basement membrane may be seen in 

 some cases entirely denuded of epithelium ; 

 in other tubes a few granular particles of the 

 old and decayed epithelium remain (fig. 171.) ; 



Fig. 171. 



Section of a portion of kidney, showing the tubes 

 deprived of their epithelium by " chronic desquama- 

 tive nephritis." The tubes as they lie packed in 

 the meshes of the fibrous matrix have an appearance 

 somewhat like that of globular and oval transparent 

 vesicles or cysts. See figs. 149 c and 150. Magnified 

 200 diameters. Med. Chir. Trans, vol. xxx. 



and again, in other instances, the interior of a 

 tube which has been deprived of its proper 

 glandular epithelium is seen lined by small 

 delicate transparent nucleated cells (fig. 172.), 



Fig. 172. 



a, Section of a portion of kidney showing the 

 tubes lined by delicate transparent nucleated cells ; 

 these cells have taken the place of the normal epi- 

 thelium which has been destroyed and swept away ; 

 b, portion of the basement membrane of a tube de- 

 prived of its epithelium, and contracted by its elas- 

 ticity into an irregular globular form after being 

 detached from the surrounding tissues ; c, portion 

 of a tube much dilated, and bulging in the intervals 

 of the matrix ; the constricted portions correspond 

 with the surrounding rings of fibrous tissue. Mag- 

 nified 200 diameters. Med. Chir. Trans, vol. xxx. - 



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