EFFECTS OF GONAD GRAFTS IN CHICKS 31 



5. The process of degeneration of the right miillerian duct is 

 inhibited. In several cases the developed duct persists on the 

 right as well as on the left side. Examples: embryos with testis 

 grafts, nos. 31-3, 47-10, 43-3; embryos with ovary grafts, nos. 

 27-4, 7-3, 29-5, 1-7, 44-16. 



6. The wolffian ducts typical of one sex are associated with 

 the gonads or miillerian ducts typical of the opposite sex. I his 

 point is not, however, so striking as the other points. 



7. A black pigmentation often appears on the male-type 

 gonads. This is shown in embryos nos. 27-6, 43-3, 2-5, 17-1, 

 and 17-5. It occurs with both testis and ovary grafts. Histo- 

 logical examination of such gonads reveals that the pigment 

 granules occur not only on the surface, but extend into the interior 

 of the organ and are mingled with the tissue of the stroma. 



8. The histological changes in the affected gonads will be 

 described in detail in a later paper, and hence will be but briefly 

 summarized at this point. Histological examination shows that: 



a. The male-type gonads are structurally modified testes. 

 The tunica albuginea is abnormal and in some cases partially 

 absent. Where present the connective tissue of which it is 

 composed is much looser than in the normal albuginea. The 

 stroma between the seminiferous tubules is also much less com- 

 pact than in the normal testis. The seminiferous tubules are 

 fewer in number and more irregular in arrangement than in 

 normal testes. Within the tubules the germ cells are reduced 

 in number and inactive or degenerating, as indicated by their 

 staining behavior. 



h. The female-type gonads are structurally modified ovaries. 

 They are less modified from the normal than in the case of male- 

 type gonads. In some cases a partial disappearance of the 

 cortical layer was found; in others a degenerating or necrotic 

 condition of the cords of second proliferation was noticeable. 



c. The miillerian ducts which are associated with male-type 

 gonads are very similar in structure to the developed ducts of 

 normal females. 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 33, NO. 1 



