340 



THE ORGANS 



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tubules continuous with those of the mediastinum. The epididymis is 

 divided into three parts: an expanded upper extremity, the head or 

 globus major (Figs. 2,^3 and 234, c) ; a middle piece, the body (Fig. 234, 

 d)\ and a sHghtly expanded lower extremity, the tail or globus minor. 

 From the last named passes off the main excretory duct of the testis, 

 the vas deferens (Fig. 233, vd). All of the tubules of the epididymis 



are continuous on the one 



e a 



1 ---— r^ hand with the tubules of 



: .^'"rv the testicle, and on the 



other with the vas deferens. 

 They thus constitute a 

 portion of the complex sys- 

 tem of excretory ducts of 

 the testicle. 



The seminiferous 

 tubule may , be divided 

 with reference to structure 

 and location into three 

 parts, (i) A much convo- 

 luted part, the convoluted 

 tubule, which begins at the 

 base and occupies the 

 greater portion of a lobule 

 of the testis ^Fig. 237, a). 

 As they approach the apex 

 of a lobule several of these 

 convoluted tubules unite to 

 form (2) the straight tubule 

 (Fig. 233, s, 237). This 

 passes through the apex 

 of the lobule to the mediastinum, where it unites with other straight 

 tubules to form (3) the irregular network of tubules of the medias- 

 tinum, the retejestis (Fig. 237, c). 



I. The Convoluted Tubule. — This, which may be considered 

 the most important secreting portion of the lobule, since it is here 

 that the spermatozoa are formed, has a diameter of from 150 to 250,". 

 The tubules begin, some blindly, others by anastomoses with neigh- 

 boring tubules, near the periphery of the lobule, and pursue a tortuous 

 course toward, its apex (Fig. 237, a). 



The wall of the convoluted tubule (Fig. 235) consists of three 



Fig. 234. — Longitudinal Section through Human 

 Testis and Epididymis. X2. (Bohm and von 

 Davidoff.) The light strands are connective- 

 tissue septa, a, Tunica albuginea; b, mediastinum 

 and rete testis; c, head of epididymis; d, body of 

 epididymis; c, lobule; s, straight tubules; t, vas 

 epididymis. 



