STRUCTURE OF THE URETERS. 



943 



by the vas deferens, which passes down between the ureter and the bladder. 

 In the female, the ureters run along the sides of the cervix uteri and upper 

 part of the vagina before reaching the bladder. 



Having reached the base of the bladder, about two inches apart from one 

 another, the ureters enter its coats, and running obliquely through them for 

 about three-quarters of an inch, open at length upon the inner surface by 

 two narrow and oblique slit-like openings, which are situated, in the male, 

 about an inch and a half behind the prostate, and about the same distance 

 from each other. This oblique passage of the ureter through the vesical 

 walls, while allowing the urine to flow into the bladder, has the effect of 

 preventing its return up the ureter towards the kidney. 



Structure. The walls of the ureter are pinkish or bluish white in colour. 

 They consist externally of a dense, firm, areolar, and elastic coat, which in 

 quadrupeds decidedly contracts when artificially irritated. According to 

 Huschke, it possesses two layers of longitudinal fibres : Henle finds only an 

 inner longitudinal and an outer circular layer ; while Kolliker, who formerly 

 described the circular and outer longitudinal layers as the only layers 

 found except in immediate proximity to the bladder, now admits the inner 

 longitudinal and circular as the prin- 

 cipal layers, on Henle's authority, and Fig. 663. 

 states that the longitudinal fibres external 

 to the circular layer are absent at the 

 upper part of the tube. 



Fig. 663. EPITHELIUM FROM THE PELVIS OP 

 THE HUMAN KIDNEY (from Kolliker). ^p 



A, different kinds of epithelial cells separated ; 

 B, the same in situ. 



Internally, the ureter is lined by a thin 

 and smooth mucous membrane, which 

 presents a few longitudinal folds when 

 the ureter is laid open. It is prolonged 

 above upon the papillaa of the kidney, 

 and below becomes continuous with the 

 lining membrane of the bladder. The 

 epithelium is of the spheroidal or tran- 

 sitional character, stratified, and con- 

 taining, besides rounded cells, others 

 cylindrical and branched (Kolliker and 

 Luschka). 



Vessels. The ureter is supplied with blood from small branches of the renal, the 

 spermatic, the internal iliac, and the inferior vesical arteries. The veins end in various 

 neighbouring vessels. 



The nerves come from the inferior mesenteric, spermatic, and hypogastric 

 plexuses. 



Varieties. Sometimes there is no funnel-shaped expansion of the ureter at its upper 

 end into a pelvis, but the calyces unite into two or more narrow tubes, which afterwards 

 coalesce to form the ureter. Occasionally, the separation of these two tubes continues 

 lower down than usual, and even reaches as low as the bladder, in which case the 

 ureter is double. In rare cases, a triple ureter has been met with. 



In instances of long-continued obstruction to the passage of the urine, the ureters 

 occasionally become enormously dilated, and their opening into the bladder becomes 

 direct, so as to lose its valvular action. 



