URETER 



323 



or somewhat flattened. Their lower surface may be indented by the rounded 

 ends of several underlying cells, as is particularly the case in the contracted 

 bladder (Fig. 323). Two nuclei are often found in a superficial cell, and 



Tunica adventitia. 



Tunica 

 mucosa. 



FIG. 321. TRANSVERSE SECTION OF THE LOWER HALF OF A HUMAN URETER. X 15. 



e., Epithelium; t., tunica propria; 1, inner longitudinal muscle bundles; r, circular layer of muscle bundles 



li, outer longitudinal muscle bundles. 



in some animals they are known to arise by amitosis. Leucocytes fre- 

 quently enter the epithelium. In some animals mucous glands have 

 been found extending into the tunica propria, and there are gland-like 

 pockets in man. Some of these have no lumen and it is said that none 



FIG. 322. VERTICAL SECTION OF THE Mucous MEMBRANE OF A 



HUMAN BLADDER. X 560. 



a, Columnar cell with cuticular border; b, lymphocyte; c, tunica 

 propria. 



FIG. 323- A SUPER- 

 FICIAL EPITHELIAL 

 CELL AND Two 

 C L U B-S H A P B D 

 CELLS FROM A CON- 

 TRACTED BLADDER. 

 (Koelliker.) 



are true glands. Capillary blood vessels, which are abundant in the 

 mucosa, are found directly beneath the epithelium and present the decep- 

 tive appearance of becoming intra-epithelial. The tunica propria consists of 

 fine connective or reticular tissue, with few elastic fibers. It contains 



