208 



NORMAL HISTOLOGY. 



The seminiferous tubules may be conveniently divided into 

 three portions: (i) the tortuous convoluted tubules, whose wind- 

 ings contribute the bulk of the lobule, (2) the straight tubes, 

 situated in the apices of the pyramidal lobules, and (3) the tubules 

 within the mediastinum, which by their union form the rete 

 testis. 



(X The seminiferous tubules terminate in the mediastinum, from 

 which situation the seminal canals are continued by intermediate ves- 

 sels connecting testicle and epididymis ; these intermediate tubules 

 are the vasa efferentia and the coni vasculosi. The former arise 

 from the rete testis, while the latter are the progressively tortu- 

 ous continuations of the vasa efferentia terminating in a mass, the 



FIG. 250. 



Section of human testicle, including portion of tunica albuginea, ex- 

 hibiting general arrangement and structure of tubules : a, tunica albu- 

 ginea ; b, seminiferous tubules cut in various directions ; c, basement- 

 membrane ; d, secreting cells ; e, groups of interstitial cells ; f, intertubular 

 connective tissue. 



globus major, which represents the sum of the tortuous coni vas- 

 culosi. These last-named canals unite to form the main tube of 

 the epididymis, which is sufficiently convoluted to include its 

 entire length of twenty feet within the inconsiderable bulk of the 

 epididymis. 



The seminiferous tubules, 130-140 n in diameter, possess walls 

 which are composed of several layers of flattened endothelioid con- 

 nective-tissue plates, applied to which a thin basement-membrane 



