166 NORMAL HISTOLOGY. 



cavernous portion of the urethra it consists of but a single layer. 

 The stratified epithelium covering the glans extends for a short 

 distance from the meatus into the urethra (Fig. 144). The epithe- 



FIG. 144. 



Epithelium from the human male urethra. (Rieder.) 



lial lining rests upon fibrous tissue containing a number of elastic 

 fibres, and this is bounded externally by a muscular coat. In the 

 prostatic portion the muscular coat consists of an inner longitudinal 

 and an outer circular layer of fibres, which become less well marked 

 as the course of the urethra is followed, the circular coat disappear- 

 ing in the bulbous portion and the longitudinal fibres becoming 

 scattered toward the anterior part of the cavernous portion. The 

 mucous membrane contains little tubular glands, " LittrS's glands," 

 some of which are simple, while others are compounded. In the 

 collapsed condition the urethral mucous membrane is thrown into 

 one or more longitudinal folds. 



In the female the epithelial lining of the urethra is either strati- 

 fied or composed of a single layer of columnar cells. The glands 

 are more sparsely distributed than in the male, except for a group 

 situated near the meatus. On the other hand, the muscular coat 

 is thicker and consists throughout the course of the urethra of a 

 well-defined internal longitudinal and external circular layer of 

 fibres. 



From the pelvis of the kidney to the stratified epithelium of the 



