796 



THE REPRODUCTIVE ORGANS. 



[CH. LVII. 



contains numerous lymphatic clefts. Lying in it accompanying 

 the blood-vessels are strands of polyhedral epithelial cells, of a 

 yellowish colour (interstitial cells}. 



The tubules of the rete testis are lined by cubical epithelium ; 

 the basement membrane is absent. 



The vasa eferentia, coni vasculosi, and epididymis are lined by 

 columnar cells, with very long cilia. There is a good deal of 

 muscular tissue in their walls. 



The vas deferens consists of a muscular wall (outer layer longi- 

 tudinal, middle circular, inner longitudinal), lined by a mucous 

 membrane, the inner surface of which is covered by columnar 

 epithelium. 



The vesiculce seminales are outgrowths of the vas deferens. 



Fig. 607. Erectile tissue of the human penis, a, fibrous trabeculee with their ordinary 

 capillaries ; b, section of the venous sinuses ; c, muscular tissue. (Cadiat. ) 



Each is a much convoluted, branched, and sacculated tube of 

 structure similar to that of the vas deferens, except that the wall 

 is thinner. 



The penis is composed of cavernous tissue covered by skin. 

 The cavernous tissue is collected into three tracts, the two corpora 

 cavernosa and the corpus spongiosum in the middle line inferiorly. 

 All these are enclosed in a capsule of fibrous and plain muscular 

 tissue ; the septa which are continued in from these, form the 

 boundaries of the cavernous venous spaces of the tissue. The 

 arteries run in the septa ; the capillaries open into the venous 

 spaces. The arteries are often called helicine, as in injected 

 specimens they form twisted loops projecting into the cavernous 

 spaces (see also p. 280). The structure of the urethra and 

 prostate is described on p. 537. 



