THE URINARY BLADDER 



449 



and renal pelvis. It is therefore impossible to determine from which 

 of these portions detached epithelial cells are derived when found by 

 microscopical examination of the urine. Epithelium may become de- 



FIG. 413. TRANSVERSE SECTION OF URINARY BLADDER OF DOG. 

 a, b and c, compose the tunica mucosa; d, e and/, the tunica muscularis; g, tunica 

 serosa; a, transitional epithelium; b, lamina propria mucosse; c, deep portion ol 

 tunica mucosa, corresponding to a tela submucosa; d, internal longitudinal muscle 

 layer; e, middle circular muscle layer; /, external longitudinal muscle layer. The 

 tunica mucosa is thrown into larger and smaller folds. X 20. 



tached from any portion of the excretory passages, and as a result of 

 inflammatory changes not only the superficial cells but also the deeper 

 pear-shaped cells may be desquamated. 



The character of the epithelium varies with the collapse and dis- 

 tcntion of the organ. When empty the mucous membrane is thrown 



