THE VE8ICULJE SEMINALES. 1023 



a i'iil-de-sac ; its anterior extremity becomes constricted into a narrow straight duct, 

 which joins with the corresponding vas deferens, and forms the ejaculatory duct. 



The ejaculatory ducts, two in number, one on each side, are formed by the junc- 

 tion of the ducts of the vesiculas seminales with the vasa deferentia. Each duct is 

 about three-quarters of an inch in length ; it commences at the base of the prostate, 

 and runs forward and downward between its middle and lateral lobes, and along 

 the side of the sinus pocularis, to terminate by a separate slit-like orifice close to 

 or just within the margins of the sinus. The ducts diminish in size and also con- 

 verge toward their termination. 



Structure. The vesiculae seminales are composed of three coats : an external or 

 areolar ; a middle or muscular coat, which is thinner than in the vas deferens, 

 arranged in two layers, an outer, longitudinal, and inner, cireular ; an internal or 

 mucous coat, which is pale, of a whitish-brown color, and presents a delicate retic- 

 ular. structure, like that seen in the gall-bladder, but the meshes are finer. The 

 epithelium is columnar. 



The coats of the ejaculatory ducts are extremely thin. They are: an outer 

 fibrous layer, which is almost entirely lost after their entrance into the prostate ; a 

 layer of muscular fibres, consisting of an outer thin circular and an inner longi- 

 tudinal layer ; and the mucous membrane. 



Vessels and Nerves. The arteries supplying the vesiculae seminales are derived 

 from the middle and inferior vesical and middle haemorrhoidal. The veins and 

 lymphatics accompany the arteries. The nerves are derived from the pelvic 

 plexus. 



Surgical Anatomy. The vesiculae seminales are often the seat of an extension of the 

 disease in cases of tuberculous disease of the testicle, and should always be examined from the 

 rectum before coming to a decision with regard to castration in this affection. 



