202 



NORMAL HISTOLOGY. 



proper contain the same layers that are found in the pelvic portion 

 of the tube ; the muscular tunic, however, is somewhat better de- 

 veloped, and in the lower part of the ureter is augmented by an addi- 

 tional imperfect external longitudinal layer, although the latter is 

 represented in places by only a few scattered bundles of non-striped 

 muscle. 



THE URINARY BLADDER. 



The bladder is composed of the same coats that are found in 

 the ureter, the mucous, the muscular, and the fibrous, together 

 with the serous surface in those parts of the organ which possess 

 a peritoneal covering. The epithelium of the bladder corresponds 



to that lining the ureter and 



FIG. 245. the renal pelvis, being of the 



stratified squamous ' ' transi- 

 tional" type. The mucous 

 membrane at the base of the 

 bladder contains small race- 

 mose glands ; minute lymph- 

 follicles are also found within 

 the mucosa. The involun- 

 tary muscle is arranged in 

 three general layers, an in- 

 ner and an outer longitu- 

 dinal enclosing a middle 

 circular stratum ; the bun- 

 dles composing these tunics 

 are, however, so irregularly 

 disposed that the layers are 

 very imperfectly defined. At 

 the base of the organ the inner 

 longitudinal muscular bundles 

 increase in size, while those of 

 the augmented circular layer 

 constitute the internal vesical 

 sphincter. 



The blood-vessels of the 

 ureter and the bladder sup- 

 ply the muscular and mucous 

 coats with rich capillary net- 

 works, the one situated within 

 the mucosa of the bladder being especially rich. The lymphatics 

 have much the same distribution as have the blood-vessels, net- 

 works being found within the deeper layers of the mucosa, as well as 

 more sparingly within the muscular tissue. The nerves supplying 



Section of human bladder: a, squamous epithelium 

 covering the folds of the tunica propria ; b, submucous 

 tissue ; c, d, irregularly-disposed circular and longi- 

 tudinal bundles of non-striped muscle ; e, fibrous tis- 

 sue of serous coat. 



