222 



NORMAL HISTOLOGY. 



the bladder, the circular fibres aid in forming the internal vesical sphincter. 

 The lower end of the urethra is embraced by the anterior fibres of the 

 sphincter vaginae muscle, and higher, between the layers of the triangular 

 ligament, the canal is surrounded by the bundles of the compressor urethrae. 

 The deepest part of the mucosa and the adjacent portion of the longitudinal 



Surface 

 epithelium 



Glands 



Longitudinal 

 muscle 



Circular 

 muscle 



FIG. 272. Longitudinal section of wall of female urethra. X 50. 



muscle layer in places contain such a rich venous plexus that the tissue 

 resembles a cavernous structure. 



The blood-vessels supplying the urethra provide a generous capillary 

 network beneath the epithelium; it is, however, the unusual abundance of 

 the venous channels that confers the exceptional cavernous character to the 

 wall of the canal. The lymphatics are also numerous within the deeper 

 parts of the mucosa in the male, especially in the region of the glans penis; 

 towards the upper end of the urethra they diminish, those from the prostatic 

 portion communicating with the intramuscular network at the neck of the 

 bladder. The lymphatics of the female urethra correspond with those of 

 the membranous and prostatic portions of the male duct. The nerves 

 include branches from the pudic (sensory fibres to the mucous membrane 

 and motor fibres to the associated striped muscle) and from the hypogastric 

 plexus of the sympathetic by way of the prostatic and cavernous plexus. 

 The plexiform sympathetic fibres, associated with numerous ganglion-cells 

 along their course, supply the involuntary muscle and the walls of the blood- 

 vessels. The sensory fibres are distributed to the mucous membrane in 

 which they end mostly as free, but to some extent as special terminations 

 within the tunica propria, although some filaments penetrate between the 

 epithelial cells. 



THE SUPRARENAL BODIES. 



These are a pair of cocked-hat-shaped organs, about 6.5 cm.- long and 

 half as broad, situated at the back of the abdominal cavity, on the inner 

 aspect of the upper ends of the kidney. This proximity suggests, as a 

 matter of convenience, the description of the suprarenal body in connection 

 with the urinary organs; it must be understood, however, that the supra- 

 renal has neither morphological nor functional relations to the kidney which 

 warrant such association. 



