MALE ACCESSORY REPRODUCTIVE ORGANS 231 



uterus in the female. This vesicle, which is a small cul-de-sac, 

 and in Man lies hidden by the prostate, is probably almost or 

 quite functionless, but it has a few very small glands which 

 open into its cavity. In some animals such as the goat, for 

 example it is of comparatively large dimensions, the upper part 

 being divided into two horns. In connection with it is a 

 structure corresponding to the hymen of the female. On the 

 floor of the prostatic portion of the urethra is an elevation of 

 the mucous membrane and underlying tissue, known as the 

 crista urethra or caput gallinaginis. This eminence (which con- 

 tains erectile tissue) serves when distended with blood to 

 prevent the semen from passing backwards to the bladder, 

 and mingling with the urine in the process of emission. It is 

 assisted in this function by the contraction of the sphincter of 

 the bladder. 



The urethra in the female corresponds to that part of the 

 male urethra which is anterior to the openings of the ejaculatory 

 ducts. It is lined with a stratified scaly epithelium, like that of 

 the vagina into which it opens. Communicating with the 

 female urethra are two complex tubular glands known as 

 the glands of Skene. Their ducts open very close to the 

 urethral aperture. 



THE VESICUL^E SEMINALES 



The seminal vesicles are offshoots from the lower ends of 

 the vasa deferentia. They consist in Man of coiled tubes, about 

 five inches long, into which several diverticula sometimes open. 

 The structure of the vesicles is similar to that of the sacculated 

 part of the vas deferens, but the muscular layers are relatively 

 thinner. 



There has been some dispute as to the chief function of 

 the seminal vesicles. According to one view, they serve mainly 

 as receptacles for the spermatozoa before ejaculation. Most 

 authorities, however, are disposed to lay greatest stress upon 

 their secretory function. 



Rehfisch l has shown that if fluids are injected into the 



1 Kehfisch, " Neuere Untersnchungen iiber die Physiologic der Samen- 

 blasen," Deutsche med. Wochenachr., vol. xxii., 1896. 



