780 



EMBRYOLOGY 



The muscular coat presents three layers ; an external, rather thick layer 

 of longitudinal fibres, a thin middle layer of circular fibres, and a thin 

 layer of longitudinal fibres, all of the non-striated variety. By the action 

 of these fibres the vessel may be made to undergo energetic peristaltic 

 movements, and this has followed stimulation of that portion of the 

 spinal cord corresponding to the fourth lumbar vertebra, which is 



described by Budge as the 

 genito-spinal centre. 



The mucous membrane of 

 the vas deferens is pale, 

 thrown into longitudinal folds 

 in the greatest part of the 

 canal, and presents a number 

 of additional rugae in the sac- 

 culated portion, these rugae 

 enclosing little irregularly- 

 polygonal spaces. The mem- 

 brane is covered with co- 

 lumnar epithelium which is 

 not ciliated. In the saccu- 

 lated portion are large num- 

 bers of mucous glands. 



Attached to the vas de- 

 ferens, near the head of the 

 epididymis, is a little mass 

 of convoluted and sacculated 

 tubes, called the organ of 



Fig. 212. Vesicula seminales, vasa deferentia and ejacu- GiraldeS, Or the COrpUS 



inatum. The body is 



to 4- 



Mi- 



milh- 



A, A, vesiculse seminales ; i, i, 2, vasa deferentia -5 ? r u / o - 



right seminal vesicle ; 4, junction of the vas deferens with Ol an mcn v4-2 to 8.5 



the duct of the seminal vesicle; 5, 6, ejaculatory ducts; meters) long and -A of an inch 



7, left lobe of the prostate ; 8, median groove ; 9, membra- / . . 



nous urethra. (2.1 millimeters) broad. Its 



tubes are lined with cells of 



squamous epithelium, which often are filled with fatty granules. Usually 

 the tubes present only blind extremities, but some of them occasionally 

 communicate with the tubes of the epididymis. This part has no physio- 

 logical importance. It was regarded by Giraldes as the remnant of 

 the Wolffian body, analogous to the parovarium. 



Vesicute Seminales. Attached to the base of the bladder and situ- 

 ated externally to the vasa deferentia, are the two vesiculse seminales. 

 These bodies are each composed of a coiled and sacculated tube, four to 

 six inches (10 to 15 centimeters) in length when unravelled, and some- 



