Tin: URINARY SYSTE^r 337 



the basement membrane is the usual single layer of small cuboidal 

 cells. In the moderately distended bladder the superficial cells 

 become flatter and the entire epithelium thinner (Fig. 232). In the 

 distended organ there is still further flattening of the superficial cells 

 and thinning of the entire epithelium. The stroma consists of fme 

 loosely arranged connective tissue containing many lymphoid cells 

 and sometimes small lymph nodules. It merges without distinct 

 demarcation into the less cellular submucosa (Fig. 232, c). 







'^■=^^-^ ■ ■ ' • • V --. 





/ 



Fig. 232. — Vertical Section through Wall of moderately distended Human Bladder. 

 X60. (Technic 5, p. 331.) a, EpitheHum, b, stroma, of mucous membrane; c, sub- 

 mucosa; d, inner muscle layer; e, middle muscle layer;/, outer muscle layer. 



The three muscular layers of the lower part of the ureter are con- 

 tinued on to the bladder, where the muscle bundles of the different 

 layers interlace and anastomose, but can be still indistinctly differ- 

 entiated into an inner longitudinal, a middle circular, and an outer 

 longitudinal layer (Fig. 232, d, e,f). 



The fibrous layer is similar to that of the ureter, and attaches the 

 organ to the surrounding structures. 



The blood- and l5miph -vessels have a distribution similar to those 



of the ureter. 

 22 



