THE URINARY ORGANS. 647 



PARASITES. 



Echinococcus, iii its ordinary form of mother and daughter cysts, is 

 sometimes found in the kidney. The cysts may open into the pelvis of 

 the kidney, into the pleura, or through the wall of the abdomen. 



Cysticercus cellulosse is of very rare occurrence. Filaria sanguinis homi- 

 nis is found in the arteries, veins, lymphatics, and stroma, and may 

 pass into the urine. Strongylus gigas has been found several times in the 

 pelvis of the kidney. 



The Urinary Bladder. 



M a 1 for m at ion s . 



ABSENCE OP THE BLADDER is of rare occurrence. The bladder may be very small, 

 the urine passing almost directly into the urethra. The bladder may be separated into 

 an upper and a lower portion by a circular constriction. It may be completely divided 

 by a vertical septum into two lateral portions. Diverticula of the wall of the bladdei 

 are sometimes found in new-born children. Partial or complete closure of the neck of 

 the bladder may occur. This may lead to hydronephrosis, or the urine may be dis- 

 charged through the open urachus. 



EXSTROVERSION of the bladder is one of the most frequent malformations, and may 

 occur in either sex. It presents several varieties: 



1. The umbilicus is lower down than usual, the pubic bones are not united at the 

 symphysis, the pelvis is wider and shallower than it should be. Between the umbilicus 

 and pubes the abdominal wall is wanting. In its place is a projecting, ovoid mass of 

 mucous membrane, in which may be seen the openings of the ureters. The penis is 

 usually rudimentary ; the urethra is an open fissure (epispadias) ; the clitoris may be 

 separated into two halves. The ureters usually open normally ; sometimes their open- 

 ings are displaced or are multiple. They may be dilated. 



2. There may be a fissure in the abdominal wall, filled up by the perfectly formed 

 bladder. 



3. The umbilicus may 'be well formed, and there is a portion of abdominal wall 

 between it and the exstrophied bladder. 



4. The external genitals and urethra may be well formed, and the symphysis pubis 

 united, while only the bladder is fissured. 



5. The genitals, urethra, and symphysis may be well formed, the bladder closed 

 except at the upper part of its anterior wall. The bladder is entirely or in part inverted 

 and pushed through the opening in the abdominal wall. 



The URACHUS normally remains as a very small canal, 5 to 7 cm. long, with 

 a small opening into the bladder, or entirely closed at that point. If there is a congen- 

 ital obstruction to the flow of urine through the urethra, the urachus may remain open 

 and the urine pass through it. Or the bladder may present, even in the adult, a slender 

 disteution reaching close to the umbilicus as the result of a persistent urachus. 



Changes in Size and Position. 



DILATATION. This may be general or partial, leading to the formation of diver- 

 ticula. 



General dilatation of the bladder is produced by the accumulation of urine in con- 

 sequence of some mechanical obstacle to its escape, or of paralysis of the muscular 

 walls of the organ. The dilatation is usually uniform and may be very great, so that 

 the bladder may reach to the umbilicus. If the walls of the bladder are paralyzed, or 



