REPRODUCTIVE ORGANS IN THE MALE. 295 



a prostatic portion, a membranous portion, and a 

 spongy or penile portion. 



1. The prostatic portion is about one and one- 

 fourth inches in length and passes through the 

 prostate gland. This is the widest portion of the 

 urethra and passes vertically from the neck of the 

 bladder to the triangular ligament of the perineum. 

 In cross section the canal is crescentic with its con- 

 vexity turned forward. The lining membrane pre- 

 sents longitudinal folds, and along the posterior 

 wall is a prominent median ridge which gives rise to 

 the crescentic form of the urethra when seen in sec- 

 tions. This ridge is called the crista, or uerumon- 

 tanum. The longitudinal groove on each side of the 

 crista is called the prostatic sinus, which is pierced 

 by numerous orifices of the prostate gland. In the 

 middle of the crista is the orifice of a blind recess, 

 and at the lateral margins of this are the slit-like 

 openings of the seminal or ejaculatory ducts. The 

 median or blind recess is a cul-de-sac which passes 

 upward and backward for a distance of one-fourth 

 to one-half inch, and is called the sinus pocularis 

 or masculine uterus. It represents embryologically 

 the fused ends of Miiller's duct, and is therefore mor- 

 phologically equivalent to the female uterus. The 

 epithelium of this part of the urethra resembles that 

 of the bladder and is of the transitional variety. In 

 the sinus pocularis it is said by some to be simple 

 ciliated like that of the uterus. 



2. The membranous portion is about three-fourths 

 inch in length and lies between the two layers of the 

 triangular ligament. It is the narrowest part of the 



