THE URINARY ORGANS. 657 



The most frequent position of strictures is at the junction of the membranous and 

 spongy portions of the urethra, or close to this point. They also occur at the fossa 

 navicularis and the meatus, but frequently in the prostatic portion. There may be one 

 stricture or several. The consequences of stricture are dilatation of the urethra, the 

 bladder, the ureters, and hydronephrosis : inflammation and ulceration of the urethra 

 behind the stricture, with perforation, infiltration of urine, or the formation of fistula. 



The urethra may also be obstructed by folds of the mucous membrane ; by muscular 

 valves at the neck of the bladder; by wounds; by polypi and swollen glands; by new 

 growths; by changes in the prostate and perineum; by calculi, mucus, blood, and 

 echinococci coming from the bladder; by foreign bodies introduced from without. 



PROLAPSE and inversion of the mucous membrane occur occasionally in young 

 girls and women. There is a bluish-red swelling, from the size of a pea to that of a 

 walnut, at the meatus. In the male invagination of the mucous membrane of the ure- 

 thra has been seen after injuries of the perineum. 



WOUNDS- RUPTURE PERFORATION. 



Wounds of the urethra are produced in many ways, but most com- 

 monly by catheters and bougies. The wounds may cicatrize, or there 

 may be infiltration of urine or the formation of fistulas or false passages. 



Ruptures of the urethra are produced by severe contusions and by 

 fracture of the pelvic bones. Extravasations of blood and urine, and 

 gangrenous inflammation of the surrounding soft parts, are the ordinary 

 results. 



Ulceration and perforation of the urethra may lead to the formation 

 of fistulse, which open in various directions through the skin. 



INFLAMMATION. (Urethritis.) 



Catarrhal Urethritis may be due to the action of chemical irritants, and 

 to the extension to the urethra of inflammation from other parts ; but its 

 most frequent excitant is the gonococcus. In its acute form it involves 

 either a portion or the whole of the urethra. The mucous membrane 

 is red, swollen, and covered with muco-pus. The epithelium may be 

 loosened or exfoliated ; pus cells are present in the submucosa between 

 the epithelial cells. The gouococcus is present usually in considerable 

 numbers in the exudate, both free and in the pus cells. It may pene- 

 trate between the epithelial cells. 



Resolution may follow acute gonorrhoaal urethritis. But the condi- 

 tion may become chronic and then is often confined to the posterior por- 

 tions of the urethra. Here the gouococcus may persist for a long time 

 and may be mingled with the exudate, which is now less purulent and 

 consists very largely of mucus which in thread-like forms may be passed 

 with the urine. 



Chronic Inflammation of the urethra may exist for a long time with 

 the production of a muco-purulent exudation, but without the occur- 

 rence of marked structural lesions. In other cases it leads to ulceration, 

 to fibrous induration of the wall of the canal (see Fig. 418), to indura- 

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