THE SEMINAL VESICLES. 



1957 



Bladder, longi- 

 tudinal muscle 

 exposed 



Vas deferens 



Ureter 



— Ampulla 

 Seminal vesicle 



Ejaculatory duct 



Membranous urethra 



Cowper's glands 



Dissection showing seminal ducts and vesicles, prostate 

 and Cowper's glands ; viewed from behind. 



organs taper, often abruptly, at their lower ends to join the spermatic ducts. Usually 

 from 4-5 cm. in length, sometimes much longer and relatively slender and at others 

 short and broad, the seminal vesicles vary greatly in size and in the detail of arrange- 

 ment of their component parts and not infrequently are markedly asymmetrical, the 

 right one being often, but not in- 

 variably, the larger. Fig. 1665. 



Divested of the fibro-muscular 

 tissue that invests the organ as its 

 capsule and blends its divisions into 

 a tuberculated common mass, each 

 vesicle may be resolved into a chief 

 duct and diverticula. The former 

 — from 10-12 cm. (4-5 in.) in 

 length — ends blindly after a more 

 or less tortuous course, its terminal 

 part often describing a sharp hook- 

 like returning curve (Fig. 1667). 

 From the main canal an uncertain 

 number (from four to eight or 

 more') of blind tubular diverticula 

 branch at varying angles and in 

 different directions and by their 

 tortuosities add to the complexity 

 of outline. The lumen of the chief 

 duct, as seen in section, is irregu- 

 lar, constrictions and dilatations 

 following one another with little 

 regularity. The opening of the 

 duct into the lateral wall of the vas 



deferens is large in comparison with the terminal lumen of the ejaculatory duct, thus 

 favoring the entrance of the secretions temporarily stored within the ampulla into the 

 sacculated vesicle. The latter contains a fluid of light brownish color in which sper- 

 matozoa are nearly always found during the period of sexual activity. 



Relations. — The seminal vesicles, together with the ampullae, lie embedded 

 within a dense fibro-muscular layer, so that their position remains relatively fixed, 

 especially below, and to a certain degree independent of the changes in volume of the 



bladder and the rectum, neither 

 Fig. 1666. of which they directly touch. 



Although when distended these 

 organs are in close relation with 

 the seminal vesicles, when empty 

 the bases of the latter lie laterally 

 and at some distance from both 

 the vesical and rectal wall, sur- 

 rounded by numerous veins that 

 continue the prostatic and vesi- 

 cal plexuses. The lower half 

 of the seminal vesicles and the 

 ampullae lie behind the fundus 

 of the bladder, their axes ap- 

 proximately corresponding with 

 the sides of the vesical trigone 

 and embracing the retroureteric 

 fossa, which part of the bladder- 

 wall, when distended, may pro- 

 ject between and even displace laterally the seminal ducts and vesicles. In passing 

 from the slightly expanded bladder onto the rectum, the peritoneum covers the 

 upper fourth of the seminal vesicles and the adjoining part of the ampullae. The 



' Pallin : Archiv f. Anat. u. Entwick., 1901. 



Seminal vesicl 



Ejaculatory ducts 



Cast oJ ampullae and seminal vesicles, showing wind- 

 ings and sacculations of lumen. (Pallin.) 



