THE HUMAN PROSTATE GLAND 343 



ejaculatory ducts becomes much larger than either of these struc- 

 tures. It passes through the wall of the prostatic urethra in 

 company with them and opens in the midline just below the open- 

 ings of the ejaculatory ducts. In the sixteen weeks old fetus the 

 utricle seems to be composed of two partially fused tubes. Its 

 upper end is obliterated and nothing is seen of it until the point 

 is reached where the ejaculatory ducts and their envelopes are 

 entirely within the posterior wall of the prostatic urethra. It 

 opens below the mouths of the ejaculatory ducts. The utricle 

 begins between the ejaculatory ducts before they enter the pros- 

 tate in the twenty-two weeks old fetus as shown in fig. 6. It is 

 very much larger than those observed in other specimens and 

 shows other peculiarities already described. In all of the speci- 

 mens older than twenty-two weeks the utricle appears only in the 

 tip of the verum montanum. It opens in the middle line and in 

 nearly every case below the openings of the ejaculatory ducts. 

 In none of the specimens studied has there been found a single 

 case in which an ejaculatory duct for a prostatic tubule opened 

 into the utriculus prostaticus. There is no evidence that its 

 mouth is protected in any way from invasion of substances or 

 organisms in the posterior urethra. 



7. Below the apex of the prostate there is noted in some cases 

 a large number of glands of Littre. They are quite large and some 

 of them have branches. They do not extend into the muscular 

 layers of the urethra. They become very few in number lower 

 down in the urethra. 



CONCLUSIONS 



1. The mucosa is always free from folds over the fetal trigo- 

 num vesicae. The musculature of the bladder wall, trigonum, 

 and sphincter begins to develop at the thirteenth week and by 

 the sixteenth week is very pronounced. 



2. The subtrigonal glands begin to develop at the twentieth 

 week. They are found at all ages after that, are few in number 

 and insignificant in appearance, their only importance being that 

 they occupy a strategic position where a small pedunculated 

 enlargement might cause great obstruction to urinary outflow. 



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



