THE STRUCTURE OF FREE-MARTIN GONADS 99 



Sertoli-cell syncytium is free from male germ cells of all stages, 

 so that its normal structure can be easily observed. This is a 

 point of considerable interest, as it is the only region in the semi- 

 niferous tubule that furnishes an unobstructed view of the nor- 

 mal syncytium. So far as the writer is aware, this zone has not 

 been used before in describing the normal structure of the 

 syncytium. 



The rete tuhules and tiibuli recti. As in the other free-martin 

 gonads, the rete region is an eccentrically placed core of anasto- 

 mosing tubules, which enters the anterior end of the gonad and 

 projects posteriorly. The distance that it penetrates posteriorly 

 into the sex-cord region varies; in case 44 it penetrates about 

 half the length of the gonad, in case H-46 it penetrates to the 

 posterior end of the sex-cord region, probably also in case H-37 

 (the extent was not determined, but owing to the extreme 

 transformation of the gonad, it is probable that it penetrated to 

 the posterior end). The eccentric position of the rete has been 

 considered above under the description of the sex-cord region. 



The rete of the free-martin gonad, like that of the normal 

 testis, consists of a network of strands of coarse connective- 

 tissue fibers, in which are anastomosing tubules. The strands 

 of connective tissue are as wide in H-37 as in the normal rete 

 testis, but in cases 44 and H-46 are comparatively narrow. 

 Resting upon the wall of the rete tubule is a lining of columnar 

 epithelial cells, which resemble in a very striking degree the 

 normal condition (compare figures 14 and 15). The lumina of 

 the tubules are wider in more highly transformed gonads, so that 

 the rete region appears less compact than in the less transformed 

 gonads. 



In each gonad of this group branches of the rete tubules have 

 established connections with the seminiferous tubules. Figure 

 16 shows the abrupt transition from the seminiferous tubule into 

 a straight tubule in H-37. The seminiferous tubule is filled with 

 a stringy syncytium of Sertoli cells, while the straight tubule 

 contains a lumen and is lined with low columnar epithelial cells. 

 Comparison with figure 13 shows the transitional zones to be 

 similar. These straight tubules are most numerous in H-37, 



