THE DUCTUS DEFERENS THE SPERMATIC CORD 575 



Vessels and Nerves.— The blood supply is derived from the external pudic 

 artery, and the veins go chiefly to the external pudic vein. The nerves are derived 

 from the ventral branches of the second and third lumbar nerves. 



THE DUCTUS DEFERENS 



This tube, also commonly termed the vas deferens, extends from the tail of the 

 epididymis to the pelvic part of the urethra. It ascends in the inguinal canal, 

 enclosed in a fold detached from the medial surface of the mesorchium, near the 

 posterior (attached) border of the latter. At the vaginal ring it separates from the 

 other constituents of the spermatic cord, and turns backward and inward into the 

 pelvic cavity (Fig. 370). For some distance it lies in the free edge of the genital 

 fold, by which it is attached to the inguinal part of tlic abdominal wall and the 

 ventral part of the lateral wall of the pelvis. In its further course (over the dorsal 

 surface of the bladder) it leaves the edge of the fold and inclines medially between 

 its layers, and comes in contact with the medial face of the vesicula seminalis. Over 

 the neck of the bladder the two ducts lie very close together, flanked laterally by the 

 necks of the vesicul^e seminales, and having the uterus masculinus between tliem. 

 They then disappear under the isthmus of the prostate, and are continued through 

 the wall of the urethra to open in a small diverticulum on the colliculus seminalis 

 with the excretory duct of the vesicula seminalis. The common opening is the 

 ejaculatory orifice (Orificium ejaculatorium). 



^ It has been customary to describe a short tube, the ejaculatory duct, as resulting from the 

 union of the ductus deferens and the duct of the corresponding vesicula seminalis. Such a duct, 

 about 18-20 mm. (ca. % in.) long, exists in man as the morphological continuation of the ductus 

 deferens. In the domestic animals it is not present, since the ductus deferens and duct of the 

 vesicula seminaUs open either in common or alongside of t>;ich other in a diverticulum or evagina- 

 tion of the mucous membrane on the side of the colliculus seminahs. 



From its origin until it reaches the dorsal surface of the bladder the ductus 

 deferens has a uniform diameter of about a quarter of an inch (ca. 6 mm.). It then 

 forms a fusiform enlargement, the ampulla ductus deferentis (Fig. 517) ; this part 

 is about six to eight inches (ca. 15 to 20 cm.) long, and in its largest part nearly an 

 inch (ca. 2 cm.) in diameter in the stalhon; in geldings the enlargement is usually 

 not very pronounced. Beyond the ampulla the duct abruptlj^ diminishes in size.^ 



Structure. — The wall of the ductus deferens is thick and the lumen very small, 

 so that the tube has a firm and cord-like character. It is covered with peritoneum, 

 except in the last few inches of its course. The loose adventitia contains numerous 

 vessels and nerves. The thick muscular coat consists of longitudinal and circular 

 fibers. The mucous membrane has an epithelium of short columnar cells. In the 

 posterior part of the tube, and especially in the ampulla, there are numerous glands. 



Vessels and Nerves. — The arteries are branches of the spermatic, umbilical, 

 and internal pudic arteries, and the nerves come from the pelvic plexus of the 

 sympathetic. 



THE SPERMATIC CORD 



The spermatic cord (Funiculus spermaticus) consists of the structures carried 

 down by the testicle in its migration through the inguinal canal from the abdominal 

 cavity to the scrotum. It begins at the abdominal inguinal ring, where its constitu- 

 ent parts come together, extends obliquely downward through the inguinal canal, 

 passes over the side of the penis, and ends at the attached border of the testicle. 

 It consists of the following structures : 



(1) The spermatic artery. 



^The term "ampulla" is not entirely satisfactory, since it is likely to be interpreted to mean a 

 dilatation. There is no increase here in the lumen of the tube, and the increase in size is caused 

 by a thickening of the wall, due to the presence of numerous branched tubular glands. The term 

 "pars glandularis, " suggested by Schmaltz, seems worthy of adoption. 



