41S 



THE UEETERS. 



of the cervix uteri and upper part of the vagina before reaching the 

 Lladder, 



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 gland, 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 reflux. 



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



colour. They consist of an external 

 fibrous coat, a middle coat of plain 

 muscnlar tissue, and a mucous lining. 

 According to Huschke and Obersteiner 

 the muscular coat possesses two layers 

 of longitudinal fibres and a middle 

 circular layer : Henle finds only an 

 inner longitudinal and an outer cir- 

 cular layer ; while IvoUiker, who ad- 

 mits the inner longitudinal and the cir- 

 cular as the principal layers, describes 

 longitudinal fibres external to the cir- 

 cular layer which are absent at the 

 upper part of the tube. 



The mucous mcmhrane, thin and 

 smooth, presents a few longitudinal 

 folds when the ureter is laid open. 

 It is prolonged above to the papilla? 

 of the kidney, and below becomes 

 continuous with the lining membrane 

 of the bladder. The epithelium (fig. 

 303) is of a peculiar character, like 

 that of the bladder. It is stratified, 

 consisting of at least three layers of 

 cells, in the uppermost of which the 

 cells are somewhat cubical, with de- 

 pressions on their under surface, vrhicli 

 fit upon the rounded ends of a second layer of pear-shaped cells ; then 

 follow one or more layers of rounded or oval cells, with processes 

 extending down to the mucous membrane. 



Vessels and nerves. — The ureter is supi^lied Avitli 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 hj'pogastric plexuses. They fomi a plexus in the 

 outer coat, containing a few ganglion-cells. 



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

 its vipper end into a pelvis, but the calices unite into two or more narrow tubes, 

 which afterwards coalesce to form the ui'eter. Occasionally, the separation of 

 these two tubes continues lower down than usual, and even reaches as low as the 

 bladder, in which case the m-eter 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 

 jireters occasionally become enormously dilated, and their opening into the 

 bladder becomes direct, so as to lose its valvular action. 



Fig. 303.— El'lTHELIUM FROJI THE 



Pelvis op the Human Kidney 

 (Kolliker). 350 Diameters. 

 A, different kinds of epithelial 

 cells separated ; B, the same in situ. 



