THE DEFEEENT DUCT. 



1289 



a lobule of the epididymis (O.T. conus vasculosus). Within the head of the 

 epididymis the little canals finally open into the single much-convoluted tube 

 which constitutes the chief bulk of the epididymis, and is called the duct of the 

 epididymis. This canal, which is not less than 19 or 20 feet in length, may be 

 said to begin in the head of the epididymis, and to end, after an extraordinarily 

 tortuous course, at the tail by becoming the ductus deferens (Fig. 1006). 



In most cases one or more slender convoluted diverticula from the duct of the epi- 

 didymis may be found near its lower end. These receive the name of ductuli aberrantes, 

 and one of them which is very constantly present often measures a foot or more in 

 length. 



Minute Structure. The duct of the epididymis and the efferent ductules are 

 lined by a ciliated epithelium, the cilia of which maintain a constant current towards 

 the ductus deferens. The duct of the epididymis possesses a muscular coat composed of 

 an inner stratum of transversely and an 

 outer stratum of longitudinally directed 

 fibres. The wall, at first thin, becomes 

 much thicker as the ductus epididymidis 

 approaches the ductus de'ferens. 



Vessels and Nerves of the Testis. The 

 testis is supplied by the internal spermatic artery, 

 a branch of the aorta. This slender vessel, after 



Head of epididymis 



Tail of 

 epididymis 



FIG. 1006. 



DIAGRAM to illustrate the structure of the testis 

 and epididymis. 



c. Duct of epididymis. v.e. Ductuli efferentes testis. 



c.v. Lobuli of epididymis. 

 r.v. Rete testis. 



Head of epididymis 



Appendix of testis 



Testi 



Cut edge c 



tunica -^aa 

 vaginali 



Pampiniform 

 plexus 



Tubuli seminiferi recti. 



Duct of epididymis 



FIG. 1007. LEFT TESTIS AND EPIDIDTMIS VIEWED 

 FROM BEHIND, showing the ductus epididymidis 

 and the first part of the ductus deferens. 



a long course, reaches the posterior border of the testis, where it breaks up into branches 

 which enter the mediastinum testis, and are distributed along the septa and on the deep surface 

 of the tunica albuginea. 



The veins issuing from the posterior border of the testis form a dense plexus, called the plexus 

 pampiniformis, which finally pours its blood through the spermatic vein, on the right side, into the 

 inferior vena cava ; on the left side the spermatic vein joins the left renal vein. 



The nerves for the testis accompany the internal spermatic artery, and are derived through 

 the .aortic and renal plexuses from the tenth thoracic segment of the spinal medulla. The 

 afferent fibres from the epididymis appear to reach the spinal medulla through the posterior 

 roots of the eleventh and twelfth thoracic and first lumbar nerves. The arteries and nerves of 

 the testis communicate with those on the lower part of the ductus deferens, namely, with the 

 artery of the ductus deferens and with twigs from the hypogastric plexus. 



The lymph-vessels of the testis pass upwards in the spermatic funiculus, and end in the 

 lumbar lymph -glands. 



DUCTUS DEFERENS. 



The ductus deferens (O.T. vas deferens) is the direct continuation of the duct 

 of the epididymis. Beginning at the inferior extremity of the epididymis, it ends, 

 after a course of nearly 18 inches, by opening as the ejaculatory duct into the 

 prostatic or first part of the urethra. The duct in parts of its course is somewhat 

 convoluted, and the actual distance traversed by it is not more than 12 inches. 

 Placed in the first instance outside the abdominal cavity, the ductus deferens ascends 



