MECHANISM OF THE DESCENT OF THE 



TESTICLE UNDER THE ACTION 



OF SEX HORMONES 



THE ELUCIDATION of the mechanism of testicular descent in the postnatal 

 period has lately made real progress. The use of active hormones has 

 demonstrated that the migiation of the organ into its scrotal seat is unques- 

 tionably controlled by endocrine factors. 



Engle' has shown that after treatment of preadolescent rhesus monkeys 

 with gonadotrophic extracts testicular migration is hastened, a fact that has 

 been corroborated by a number of later papers, which report the use of both 

 hypophysial and pregnancy-urine extracts and extend the application to other 

 zoological groups, man included. 



Hamilton," using testosterone esters, was able to induce identical effects 

 in rhesus monkeys. Walsh, Cuyler and McCullagh^ and also Nelson and 

 Gallagher* showed that in hypophysectomized rats androgenic substances are 

 able to prevent testicular changes for some time as well as keep the organ in 

 its normal position. In squirrels, androgenic substances may induce spermato- 

 genesis in seasons of sex inactivity (Wells and Moore^). 



These results do not allow one to exclude a direct action of the hormones 

 upon the testicle. There is left open for discussion the participation of the 

 gonad in the phenomenon, regarding both the modification of its consistency, 

 dimensions, etc., as well as the influence on its own endocrine activity. 



In order to eliminate these factors, that is, to solve the paradox of the 



descent of the testicles in a castrated animal, we performed experiments with 



small paraffin pellets as substitutes for the testicular parenchyma. In such a 



way a mechanical "testicle" is maintained with exclusion of every endocrine 



function of the organ. Hamilton,'' in a study directed toward another end, 



used the technique of placing loose small paraffin spheres in the scrotum in 



order to discover whether they exert any influence on the development of the 



cremaster. Our technique and experimental pinposes are, however, quite 



different from those of this author. In the present paper, we report further 



experiments on extirpation of the scrotum and the results with regard to the 



position of the testicle. A preliminary note on the subject has already been 



published.' 



Methods 



Animals: The operation was performed on 17 rats weighing from 180 to 

 250 gm., and on 4 rhesus monkeys weighing from 3.5 to 9 kg. 



Operation: In the rats we always used the abdominal method in order to 

 avoid irritation of the scrotal and cremasteric region. The testicles were ex- 

 posed by a small suprapubic incision, from 1.0 to 1.5 cm. in length. Another 



1:389] 



