THE HUMAN PROSTATE GLAND 313 



cate with the urethra not only at its sides but also in the depres- 

 sions on each side of the verum montanum commonly referred to 

 as the prostatic furrows. 



In the posterior wall of the urethra outerward from the entrance 

 of the ejaculatory ducts and widely separated from all of the other 

 lobes of the prostate, are found four large branching tubules which 

 form the posterior lobe of the prostate. The branches of these 

 tubules are not at any place in close touch with the lateral lobe 

 tubules which extend this low in the urethral wall and there seems 

 to be a definite layer of connective and muscular tissue forming 

 around the component parts of this lobe. 



Extending along the ventral or anterior wall of the prostatic 

 urethra are observed the tubules forming the anterior lobe. Four- 

 teen ducts open into the urethra in this specimen. Most of the 

 tubules are quite small. Only two are as large and extensively 

 branching as those of the other lobes already described. 



Below the outermost tubule of the posterior lobe the urethra 

 changes its shape from the inverted semilunar type shown in the 

 drawings to a stellate shape. Extending from the walls on all 

 sides are small finger-like evaginations. Some of these are simple 

 folds in the urethral mucosa but others are developing tubules, 

 some of which have extended quite deeply into the submucous 

 tissue and a few have small branches. These are considered to 

 be the developing urethral glands. While they are quite numer- 

 ous just below the apex of the prostate, below that they are not 

 found at all. 



The seminal vesicles in this series are composed of very tortuous 

 tubes which have a thick muscular layer surrounding them and 

 communicate by means of one small duct or opening into each 

 vasa deferentia under the internal sphincter. 



The two ejaculatory ducts bound together as described above 

 become attached to the wall of the urethra below the point just 

 mentioned and gradually become more deeply implanted in the 

 thick posterior urethral wall. The utriculus prostaticus is en- 

 tirely obliterated above but appears between the ejaculatory 

 ducts in the middle of the prostatic urethra. These three struc- 



