STRUCTURE OF THE HYMEN, VAGINA, AND URETHRA. 323 



fibres, which, as has been stated above, proceed from the 

 muscularis. On this account this venous plexus may be 

 regarded as a cavernous tissue (Gussenbauer). 



The veins entering the submucosa form meshes elongated in 

 the direction of the long axis of the vagina. They unite to 

 form larger branches, which traverse the muscularis, and con- 

 stitute the plexus vaginalis. The walls of these vessels present 

 the same trabecular arrangement as is exhibited by other 

 erectile organs. 



The vaginal mucous membrane is abundantly supplied with 

 veins and lymphatics, but little is known in regard to their 

 ultimate distribution. Isolated ganglion cells, and groups of 

 the same, are found in the trunks composed of medullated 

 fibres ; the latter occur especially in those places where two or 

 more trunks coalesce. The ganglion cells, as has been already 

 noted in the case of the male genitals, are of two different sizes. 



IV. URETHRA. The epithelium lining the upper part of the 

 mucous membrane of the urethra is of a laminated transitional 

 form; the uppermost cells are club-shaped, and form short 

 cylinders ; the deeper-seated ones progressively diminish in 

 height, till at length only spheroidal and flattened cells are met 

 with. In the inferior portion, the epithelium resembles that 

 of the vestibule and vagina in being laminated and tesselated ; 

 its thickness increases towards the orifice. 



Two layers, not very well separated from one another, are 

 distinguishable in the mucous membrane, an internal (mucosa), 

 with numerous ' papillae projecting into the epithelium, and 

 an external (submucosa), which contains a cavernous structure 

 composed of a plexus of large veins. The thickness of the 

 mucosa is about 013 of a millimeter, whilst that of the sub- 

 mucosa is about five times as much. 



The tissue of the mucosa is infiltrated at numerous points 

 with cells resembling lymph corpuscles, and this infiltration is 

 so considerable that the tissue simply consists of a delicate 

 network, the interstices of which are completely filled with 

 cell-like bodies (conglobate gland substance of Henle). In 

 such parts no well-defined limit can be distinguished between 

 the cells of the mucosa and the deepest epithelial cells. 



Y2 



