VESSELS AND NEEVES OF THE TESTIS. 453 



of the Tas deferens. It is traversed by very many fine rugfe, which 

 form an alveolar structure resembling that seen in the gall-bladder, but 

 deeper and enclosing much finer meshes. The epithelium of the 

 vesiculffi is of the short prismatic kind ; its particles have a granular 

 character. 



The seminal vesicles serve as receptacles or reservoirs for the semen, 

 as is proved by a microscopic examination of their contents ; but, 

 besides this, it is probable that they secrete a peculiar fluid which is 

 incorporated with the semen. 



Tlie common seminal or ejaculatory ducts, two in number, are 

 formed on each side by the junction of the narrowed extremities of the 

 corresponding vas deferens and vesicula seminalis, close to the base of 

 the prostate gland. From this point they run forwards and upwards, 

 at the same time approaching each other, and then pass side by side 

 through the prostate between its middle and two lateral lobes. After a 

 course of nearly an inch, during which they become gradually narrower, 

 they end in the floor of the prostatic portion of the urethra by two 

 small slit- like orifices placed on the verumontanum, one on each 

 prominent margin of the opening of the prostatic sinus. For- -a short 

 distance the ejaculatory ducts run in the substance of the walls of the 

 vesicle. 



The coats of the common seminal duct, as compared with those of the 

 vas deferens and vesicula, are very thin. -The strong outer tunic almost 

 entirely disappears after the entrance of the ducts between the lobes of 

 the prostate, but muscular fibres may be traced into the prostatic por- 

 tion ; and the mucous membrane becomes gradually smoother as it 

 passes into that of the urethra. According to Henle, the muscular fibres 

 of the duct are separated by blood-vessels as it passes through the 

 prostate and form the trabecul^e of a layer of cavernous tissue. 



These ejaculatory ducts convey the fluid: contained in the seminal 

 vesicles and vasa deferentia into the urethra. Their canal gradually 

 narrows as they approach their termination, where its diameter is 

 reduced to the fiftieth of an. inch. 



VESSELS AND NERVES OP THE TESTIS. 



The testicle and its excretory apparatus receive blood-vessels and 

 nerves from sources which are different from those giving the vascular 

 and nervous supply of the coverings of those parts. 



The spermatic artery, or proper artery of the testicle, is a slender 

 and remarkably long branch, which arises from the abdominal aorta, 

 and passing down the posterior abdominal wall reaches the spermatic 

 cord, and descends along it to the gland. In early foetal life its course 

 is much shorter, as the testis is then situated near the part of the aorta 

 from which the artery arises. As the vessel approaches the testicle, it 

 gives off small branches to the epididymis, and then divides into others 

 which perforate the tunica albuginea at the back of the gland, and pass 

 through the corpus Highmorianum ; some spread out on the internal 

 surface of the tunica albuginea, whilst others run between the lobes 

 of the testis, supported by the fibrous processes of the mediastinum. 

 The smallest branches ramify on the delicate membranous septa 

 between the lobes, before supplying the seminiferous tubes. 



The vas deferens receives from the superior vesical artery a long 

 slender branch which accompanies the duct, and hence is named the 



