HUMAN TESTIS AND EPIDIDYMIS 403 



same peripheral layer of the vascular network is buried within the 

 organ, and becomes the system of arched vessels found between 

 the medulla and cortex. For in the ovary, the original or medul- 

 lary cords degenerate, and new cords (Pfliiger's cords) grow from 

 the surface, carrying before them the vessels which lay just be- 

 neath the surface. From these new vessels grow peripherally, 

 while the network, which supphed the medullary cords for the most 

 part is lost. The terminal arteries of the ovary, then, like the 

 real sexual cords, are secondary affairs when compared with similar 

 structures in the testis. 



EPIDIDYMIS 



The precursors of the epididymis are the anterior mesonephric 

 tubules, which form the ductuh efferentes, and the anterior 

 portion of the mesonephric duct, whose convolutions form a large 

 part of the head and the tail of the epididymis, while the posterior 

 part remains unconvoluted and forms the ductus deferens. As 

 in the case of the testis tubules, this paper deals with the more 

 detailed morphology of the epididymal tubules in man, especially 

 in the late embryonic and fetal stages. 



Perhaps the most accurate accounts of the Wolffian tubules 

 are those of MacCallum, who studied pig, and, less thoroughly, 

 man, and Grafe, who worked with chick material. According to 

 MacCallum the tubule of a fully formed Wolffian body, in the pig, 

 is a long affair, running from the glomerulus in sweeping curves, 

 from mesial to lateral border of the organ (see his text-figure no. 

 8). Some of these tubules were seen to branch soon after leaving 

 the Wolffian duct, others just before entering the glomeruU. 

 ''Evidences of anastomosis and the formation of networks of 

 tubules were also made out," particularly in the region of the dor- 

 sal border. MacCallum made models from serial sections and also 

 injected fresh material; the anastomoses and networks were found 

 by the latter method. Grafe also found braiiches of the tubules, 

 and affirms that they indicated new tubules which have grown by 

 budding. He also made a point of the fact that some of the tu- 



