THE STRUCTURE OF FREE-MARTIN GONADS 79 



manner; the blood-vessels enter the hilus (fig. 3), from which 

 they are distributed outwardly to the medullary cords and 

 cortex. 



It is thus seen that the distribution of the blood in a centri- 

 petal manner is characteristically a male feature, while the 

 centrifugal method is strictly a female attribute. Since the 

 free-martin gonad is an ovary which is changing into a testis, 

 as has been shown, it is not an unexpected finding that the 

 manner of the distribution of the blood-vessels should also 

 change in the male direction. This is exactly what is found in 

 the free-martin gonads of cases 66 and 42, where the blood is 

 distributed in a centripetal manner to the sex-cord region. On 

 the other hand, in case H-18 the original ovarian method is 

 retained, so that the blood is distributed in a centrifugal manner 

 to the sex-cord region. 



The peritoneal surface of the gonad consists of a single layer 

 of cuboidal epithelial cells in case 66, and of a single layer of 

 flattened epithehal cells in cases 42, H-42, and H-18. Instead 

 of the thick germinal epithelium of the normal ovary, these, as 

 well as all other free-martin gonads, are enclosed within a single 

 layer of more or less flattened epithelial cells as in the normal 

 testis. 



The sex-cord region. In this group of gonads (except in H-42, 

 which is atypical and will be considered separately) the sex- 

 cord region constitutes the largest portion of the gonad and 

 shows a moderate degree of organization of the sexual cords and 

 intercordal tissue. The latter comprises a stroma of a moder- 

 ate number of loosely arranged connective-tissue fibers, and 

 between them the so-called ijiterstitial cells. The fibers of the 

 stroma are continuous with the connective-tissue fibers of the 

 tunica albuginea and ramify throughout the sex-cord region, 

 forming a framework between the sexual cords. Histologically, 

 the stroma is composed of fusiform-shaped cells, which are 

 apparently fibroblasts of connective tissue. These cells are 

 further characterized by elongated and very prominent nuclei, 

 but the cytoplasm is scanty and quite inconspicuous. From 

 the ends of the nuclei extend fibrillar processes, which anastomose, 



