REPRODUCTIVE SYSTEM OF FREE-MARTINS 479 



SUMMARY AND CONCLUSIONS 



The conditions found in foetal free-martins described in the 

 preceding pages, show the effect of the introduction of intersti- 

 tial secretion from the male embryo into the circulation of a female 

 embryo. The possibihty of such an introduction of interstitial 

 secretion and its effect upon the secondary sex characters has 

 been fully discussed by Professor Lillie in his paper which pre- 

 cedes this. There follows a summary of the conditions result- 

 ing from the introduction of the interstitial secretion of the cf 

 embryo into the 9 embryo. 



The sex cords present in the free-martin are homologous with 

 the medullary cords of the normal female and with the seminif- 

 erous tubules of the male. In some specimens the sex cord region 

 is simply an unorganized, homogeneous mass of cells. In the 

 majority of embryos in which the cords are differentiated from 

 each other, they resemble the medullary cords of the female, 

 but in a few cases some of the cords exhibit an arrangement of 

 cells like that of the seminiferous tubules. This latter con- 

 dition is found only in free-martins in which the sex cord region 

 is large, compared with that of other free-martins. 



In no free-martin are sex cords ever formed which correspond to 

 the second set of sex cords of the female, the cords of Pfiiiger. 

 The latter are characteristic of the female and have no homologue 

 in the male. The proliferation of the cords of Pfiiiger from the 

 germinal epithelium marks the beginning of differentiation from 

 the indifferent stage to the female condition. In the male, 

 apparently all the primitive germ cells are carried down into the 

 gland with the first proliferation of the germinal epithelium, 

 leaving as the surface covering of the testis, only the thin meso- 

 thelial peritoneum from which the cords are soon separated by a 

 compact layer of connective tissue, the albuginea. In the fe- 

 male, relatively few of the primitive germ cells enter the medul- 

 lary cords. The primary albuginea, an irregular layer of loose 

 connective tissue cuts these cords off from the germinal epithe- 

 lium which is still a thick layer composed largely of cuboidal epi- 

 thelial cells, and containing also many primitive germ cells. 



