THE STRUCTURE OF FREE-MARTIN GONADS 73 



cells, the cytoplasm of which runs together, but the nuclei remain 

 distinct. The structure of this cell aggregation varies consid- 

 erably in the different sexual cords. In some the nuclei are 

 closely crowded and irregularly arranged; the amount of cyto- 

 plasm varies considerably, for in some cords it is clearly seen, 

 while in others it is hardly detectable. Such an irregular 

 arrangement and crowding of the nuclei resemble the con- 

 dition in the medullary cords of the normal ovary (N 14, table 2) 

 and of very young seminiferous tubules (N 13, table 3). In 

 other sex cords the supporting epithelium is loose and the nuclei 

 are arranged in a single layer which lines the wall of the cord. 

 The long axes of the ovoid nuclei are arranged perpendicular to 

 the wall of the sex cord, forming a palisade arrangement. From 

 the inner ends of the nuclei cytoplasmic strands extend toward 

 the potential lumen. Such sex cords are typical seminiferous 

 tubules and present a structure similar to the condition in the 

 seminiferous tubules in the testis of a young foetus, with the 

 exception that there are no male germ cells in the free-martin 

 tubules (T 16, T 6, table 3), (fig. 2, s). The nuclei of the sup- 

 porting epithelial cells of both types of sexual cords resemble 

 very closely the nuclei of the Sertoli cells of the normal adult 

 testis, in having a slight amount of chromatin, chiefly distributed 

 in a distinctive nucleolus, and a faintly staining nuclear mem- 

 brane. A few of the tubules show distinct pathological changes, 

 where the cytoplasm of the supporting epithelial cells has in 

 places disappeared, leaving naked nuclei; in others even the 

 nuclei have disappeared, leaving mere spaces in the dense con- 

 nective tissue. 



The rete tubules. Located at the hilus of both gonads is the 

 well-developed cylindrical mass of rete tubules, which con- 

 stitutes by far the greater portion of the reproductive gland in 

 case H-36. Figure 2, rt, shows the primitive position of the rete 

 in H-40 and the way it is marked off sharply from the sex-cord 

 region by connective tissue, so that no connections (tubuli recti) 

 are established between the rete tubules and the sexual cords. 

 No tubuli recti are developed in H-36. The distance of penetra- 

 tion of the rete into the sex-cord region has not been determined 

 in H-36, but in H-40 it only extends two- thirds of the way back. 



