1958 



HUMAN ANATOMY. 



Diagram showing course of main canal in preceding preparation: 

 a, ampulla ; c, seminal vesicle; 6, ejaculatory duct. {Palliti.) 



extent of this investment, however, varies with the depth of the recto-vesical pouch, 

 which in turn depends upon the degree of distention of the bounding organs, the 

 bladder and the rectum. 



Structure.— In their general make-up the seminal vesicles closely resemble the 

 ampullae, possessing a robust muscular wall composed of an inner circular and an 



outer longitudinal layer of involun- 

 FiG. 1667. tary muscle. The mucous mem- 



brane is conspicuously modelled 

 by numerous ridges and pits, so 

 that the free surface appears 

 honey-combed (Fig. 1668). The 

 epithelial covering consists of a 

 single or imperfect double layer 

 of low columnar cells, many of 

 which present changes indicating 

 secretory activity. Although true 

 glands are wanting within the 

 seminal vesicles, the minute di- 

 verticula within the epithelium 

 containing goblet-cells may be re- 

 garded as concerned in producing 

 the peculiar fluid found within 

 these sacs, which is of importance probably not only in diluting the secretion of the 

 testicle and supplying a medium favorable for the motility of the spermatic fila- 

 ments, but also in completing the volume of fluid necessary for efficient ejaculation 

 (Waldeyer). 



Vessels of the Seminal Ducts and Vesicles. — The ar/^rzV.y supplying the 

 spermatic duct are derived chiefly from the deferential, a vessel of small size but long 

 course that arises either directly 



from the internal iliac or from its Fig. 1668. 



vesical branches. On reaching the 

 duct, just above the ampulla, the 

 artery divides into a smaller de- 

 scending and a larger ascending 

 division. The former, in conjunc- 

 tion with accessory twigs from the 

 middle hemorrhoidal and the in- 

 ferior vesical arteries, generously 

 provides for the ampulla, and the 

 latter accompanies and supplies the 

 vas deferens throughout its long 

 course, finally, in the vicinity of the 

 testicle, anastomosing with branches 

 from the spermatic, — a communica- 

 tion of importance for collateral cir- 

 culation. The twigs passing to the 

 spermatic duct enter its wall and 

 break up into capillary net-works 

 within the muscular and mucous 

 layers. The rich arterial supply for 

 the seminal vesicle includes anterior 

 and upper and lower branches, con- 

 tributed by the deferential, the in- 

 ferior vesical, and the superior and 

 middle hemorrhoidal arteries. The 

 minute distribution is effected by capillary net-works to the muscular and mucous 

 coats. 



The vetJis that follow the spermatic duct as the deferential plexus, and within 

 the spermatic cord communicate with the pampiniform plexus, increase in size and 



Lumen 



Ridges on 

 free mucous 

 surface 



Mucous 

 membrane 



Muscular 

 coat 



Pits of mu- 

 cous coat 



Cross-section of seminal vesicle, showing 

 modelling of mucous surface. X i6. 



