THE ACCESSORY REPRODUCTIVE, ORGANS 241 



portion of the corresponding seminal vesicle to form the ejaculatory 

 duet. The two ejaculatory ducts, after traversing the prostate, open 

 into the floor. of tjhe urethra by small slit-like apertures. Their 

 function is to convey to the urethra the fluid contained in the 

 seminal vesicles and in the vasa deferentia. The coats of the 

 ejaculatory ducts are relatively thin. The lining epithelium is 

 similar to that of the vas deferens. 



The urethra, which serves as the common channel "for both urine 



Fig. 63. — Transverse section through the tube of the epididymis. 

 (After Szymonowicz, from Sehafer.) 



a, Blood-vessel ; 6, circular muscle fibres ; c, epithelium. 



and seminal fluid, is lined by a columnar epithelium resting on a 

 vascular corium. The latter is surrounded by submucous tissue 

 containing two layers of muscular fibres, the inner being arranged 

 longitudinally, and the outer circularly. The urethra in man is 

 usually described as consisting of three divisions, the prostatic, the 

 membranous, and the spongy portions. Of these the membranous 

 portion comprises that part of the urethra between the apex of the 

 prostate and the bulb of the corpus spongiosum, to be described 

 below. Opening medially into the prostatic portion of the urethra, 

 between the two ejaculatory ducts, is the aperture of the uterus 

 masculinus, or organ of Weber, which is the homologue of the vagina 

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



