THE HUMAN PROSTATE GLAND 311 



A very short distance below the lower part of the internal 

 sphincter there are seen numerous gland tubules which are situated 

 near the periphery of the greatly thickened urethral wall. These 

 ends of prostatic tubules are arranged in four groups which are 

 rather widely separated from one another by the stroma of the 

 urethral wall. These groups of gland tubules are located one in 

 each lateral wall, one between the floor of the urethra and ejacu- 

 latory ducts, and one in the anterior wall. Surrounding each 

 tubule is noted a slight differentiation of tissue from that com- 

 posing the wall of the urethra, which in this stage shows equal 

 thickening on all sides, and there is nolas yet any bulging, although 

 the posterior wall is enlarged as it was in the 13 weeks fetus due 

 to the presence of the ejaculatory ducts and the utriculus pros- 

 taticus with their surrounding tissue layers. 



Careful identification of the various groups of tubules mentioned 

 above and tracing their course from section to section reveals 

 the fact that even at this early stage these structures have many 

 branches which communicate with the urethra by means of one 

 rather small duct. In one case there are three extensively 

 branching tubules whose ducts join and empty into the urethra 

 through a common duct (fig. 3). 



In this series of sections the tubules are distinctly divided into 

 five different groups as follows: 



The middle lobe is composed of. ten extensively branching 

 tubules which are separated from the two lateral lobes by a rather 

 thick layer of connective tissue. The branches of these tubules 

 which are situated in the posterior wall of the prostatic urethra 

 between the ejaculatory ducts and the bladder join and communi- 

 cate with the urethra by means of ten ducts whose mouths are 

 situated upon the floor of the urethra a considerable distance 

 bladderward from the openings of the ejaculatory ducts and are 

 grouped together in a very characteristic manner, being sur- 

 rounded and bound together by connective tissue and developing 

 smooth muscle fibers (fig. 4). The location of these tubules, their 

 course as graphically shown in fig. 3 by means of a composite 

 drawing which represents the change in location of the various 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 13, NO. 3 



