THE HUMAN PROSTATE GLAND 323 



tral lobe of the prostate as they are widely separated from that 

 structure and are entirely different in their character from pros- 

 tatic tubules. All of these gland tubules extend from the urethra 

 upwards or towards the bladder under the mucosa, and in no case 

 do they extend deeply into the muscular tissue. They push out 

 into the submucous tissue between the numerous blood vessels 

 in this region and are not surrounded by a specially arranged 

 musculature. The lumina of these tubules are about three times 

 the size of the blood vessels found here, but are much smaller 

 than the prostatic gland tubules. 



The middle lobe is made up of eleven- tubules, whose blind ends 

 extend backward and upward under the sphincter of the bladder, 

 each of which has a larger number of branches and communicates 

 with the urethra through quite small ducts which open upon its 

 floor some distance above the openings of the ejaculatory ducts 

 and utriculus prostaticus. In the specimen studied previously 

 there has been a wide and distinct separation of the middle lobe 

 from the two lateral lobes. This distinctiveness is well shown in 

 the fetus 16 weeks old (fig. 4). In this specimen it is easy to dis- 

 tinguish the middle lobe from its location, the direction in which 

 the tubules extend, and the fact that its ducts communicate with 

 the urethra at the same point that ducts of middle lobe tubules 

 have in younger series. On the other hand, the layer of tissue 

 separating the middle from the lateral lobes is not very extensive 

 except at the base. There is no semblance of a special capsule 

 and in some places the tubules of the middle lobe are side by side 

 with the tubules of the lateral lobe, but in no place is there found 

 an intermingling of the branches of one lobe with those of another. 

 At the base of the prostate, up under the vesical sphincter where 

 the prostatic tubules nave grown farthest away from their point 

 of origin, the separation between the middle lobe and the two 

 lateral lobes is quite wide and there is a great deal of connective 

 and muscular tissue between them. In no case has it been possi- 

 ble to find any difference between the architecture of the tubules 

 of the different lobes with the exception that those of the middle 

 lobe are usually not quite so large as the lateral lobe tubules. 

 Finer histological studies of the glandular epithelium have not 



