THE REPRODUCTIVE ORGANS. 



247 



with each other and open into a number of straight ducts of 

 smaller diameter, called the " vasa recta." These are lined with 

 a cubical epithelium resting upon an extension of the basement- 

 membrane of the seminiferous tubes, and, in turn, open into a 

 reticulum of tubules of larger diameter, situated in the mass of 

 areolar tissue at the posterior aspect of the testis. This reticulum 

 is called the " rete vasculosum," and the tubules composing it are 

 lined with a low epithelium, apparently resting upon the surround- 

 ing fibrous tissue, without an intermediate basement-membrane. 

 These tubes permit an accumulation of semen before it enters the 

 vasa efferentia. 



The vasa efferentia have a peculiar epithelial lining, which may 

 be regarded as transitional between the cubical epithelium of the 

 vasa recta and rete and the ciliated columnar variety lining the 

 epididymis. It consists of alternating groups of cubical and 

 ciliated columnar epithelial cells (Fig. 231). 



Fig. 231. 



Section of vasa efferentia from human testis. (B6hm and Davidoff.) a, cubical or secretory 

 epithelium ; 6, columnar ciliated epithelium, with deeper pyramidal cells beneath those 

 that bear the cilia. This form of ciliated epithelium corresponds to that found in the 

 epididymis where the cubical epithelium is absent. 



The vasa efferentia, as already stated, open into the canal of the 

 epididymis, through which their contents reach the vas deferens. 

 The walls of the efferent tubes possess a layer of encircling smooth 

 muscular fibres, which are reinforced in the epididymis by an addi- 

 tional external layer of longitudinal fibres. 



The nerves supplied to the testis are destitute of ganglia, and are 

 distributed to the vessels and surfaces of the seminiferous tubules. 

 No terminations have been traced to the epithelial lining of those 

 tubules. 



