450 THE TESTICLES AND THEIR DUCTS. 



(0. Becker, 1856, corroborated in the human subject by KiiUiker). 

 The ciliary movement is stated by Becker to be in an outward direction 

 in the ducts. 



VAS DEFERENS. 



The vas deferens, or excretory duct of the testis, is a hard nearly 

 cylindrical tube, which forms the continuation upwards of the convoluted 

 canal of the epididymis. It commences at the lower end of the epi- 

 didymis, and, at first rather tortuous but afterwards becoming straight, 

 it ascends upon the inner side of the epididymis, and along the back of 

 the testicle, separated from both, however, by the blood-vessels passing 

 to and from the gland. * Continuing, then, to ascend in the spermatic 

 cord, the vas deferens accompanies the spermatic artery, veins and 

 nerves, as far as the internal abdominal ring. Between the testicle and 

 the external ring its course is nearly vertical : it lies behind the sper- 

 matic vessels, and is readily distinguished by its hard cord-like feel. It 

 then passes obliquely upwards and outwards along the inguinal canal, 

 and reaching the inner border of the internal abdominal ring, it leaves 

 tire spermatic vessels (which extend to the lumbar region), and turns 

 suddenly downwards and inwards into the pelvis, crossing over the ex- 

 ternal iliac vessels, and turning round the outer or iliac side of the epi- 

 gastric artery. Running beneath the peritoneum, it reaches the side of 

 the bladder, upon which it descends, curving backwards and downwards 

 to the under surface of that viscus, and finally passes forwards to the 

 base of the prostate gland. In its course within the pelvis, it crosses 

 over the cord of the obliterated hypogastric artery, and lies to the inner 

 side of the ureter; Beyond this point, where it ceases to be covered by 

 the peritoneum, it is attached to the coats of the bladder, in contact 

 with the rectum, and gradually approaching its fellow of the opposite 

 side. Upon the base of the bladder, the vasa deferentia are situ- 

 ated between two elongated receptacles, named the semmal vesicles ; 

 and, close to the base of the prostate, each vas deferens ends by joining 

 with the duct from the corresponding seminal vesicle on its outer side 

 to form one of the common seminal or ejaculatory ducts. 



The vas deferens measures nearly two feet in length. In the greater 

 part of its extent it is cylindrical or slightly compressed, and has an 

 average diameter of about one-tenth of an inch ; but towards its lermma- 

 tion, beneath the bladder, it becomes enlarged and sacculated, forming 

 the ampulla of Henle, and resembling in shape and structure a part ot 

 the seminal vesicle. Previously to its junction with the duct of tiiat 

 vesicle, it again becomes narrowed into a smaller and straight cylindrical 

 canal. The walls of the vas deferens are very dense and strong, and feel 

 hard to the touch, owing to the large proportion their thickness bears to 

 the inner cavity of the tube, which is scarcely more than one-sixth of 

 the whole diameter. In the sacculated portion the passage is much 

 wider, and the walls are thinner in proportion. Small simple and 

 branched tubular glands, similar to those of the vesicute seminales, beset 

 the mucous membrane of this portion of the duct (Henle). 



Besides an external areolar investment, and an internal lining mem- 

 brane, the vas deferens is provided with an intermediate thick tunic, 

 which is dense in structure, somewhat elastic, and of a deep yellowish 

 colour. This coat consists principally of longitudinal muscular fibres, 

 mixed with some circular ones. Huschke describes two longitudinal 



