640 



THE URINARY ORGANS. 



The kidney tissue in the vicinity of the abscesses may be necrotic, the 

 outlines of the cells being preserved but their nuclei absent or not re- 

 vealed by the usual staining agents. 



The infective agent may traverse the ureters in passing from the 

 inflamed bladder to the kidneys, leaving the mucous membrane of the 

 ureter intact. 



Chronic Pyelo-Nephritis. Chronic cystitis or calculi in the pelvis of 

 the kidneys may set up a chronic inflammation which involves both the 

 pelvis and calyces and the kidney tissue. The mucous membrane of the 



pelvis and calyces is thick- 

 ened, the epithelial layer 

 is changed, there is a 

 growth of granulation tis- 

 sue beneath the epitheli- 

 um, and there may be little 

 polypoid outgrowths. The 

 surface of the mucous 

 membrane is coated with 

 pus or fibrin, or the cavity 

 of the pelvis and calyces 

 are dilated and distended 

 with purulent serum (Fig. 

 400). 



The kidney itself is the 

 seat of a chronic inter- 

 stitial inflammation with 

 the production of new con- 

 nective tissue, and some- 

 times of pus, with oblitera- 

 tion of the renal tubules. 



HYDBONEPHBOSIS. 



Dilatation of the pelvis 

 and calyces of the kidneys 

 may be congenital and may 

 be associated with other 

 malformations. The pel- 

 ves and calyces of both kidneys, and the ureters, are distended with 

 urine ; the bladder may be also distended and its wall hypertrophied. 

 The urethra may be closed, or no obstruction can be demonstrated. 



In adults hydrouephrosis may follow mechanical obstruction of the 

 urethra or ureters (Fig. 401), from inflammation, tumors, or calculi. 

 According to the position of the obstruction, either one or both kidneys 

 are involved. 



The pelvis and calyces are dilated, sometimes enormously, and filled 

 with urine alone or urine mixed with pus. The kidney tissue is flat- 

 tened and thinned over the distended cavities. Its texture may remain 



FIG. 401. HYDRONEPHROSIS. 

 From obstruction of ureter. 



