392 Descent o£ the Testicle 



tachment which by contraction should induce the descent of the organ. The 

 gubernaculum testis with two moving insertions seems to play no active role 

 in the descent, in the postnatal period at least. Its Latin name means "helm 

 of the testicle," a denomination which we deem very adequate, as we agree 

 with Deming* in his statement that the gubernaculum "is either a guide or 

 rudder, but not a tractor for the testicle." On the other hand, the experiments 

 here recorded on scrotum extirpation show that even in its absence the agents 

 that impel the testicle can force the extragenital skin to distend. 



Spiral or circular contractions of the musculature of the canal comparable 

 to those which induce the progression of intestinal contents are a conjectural 

 matter, and not yet proved true. 



It seems that the most important impelling force to be taken into considera- 

 tion, mainly in animals with a lifelong permeable inguinal canal, is the ab- 

 dominal pressure; in certain cases, gravity may also be a facilitating agent. 



The most relevant role of the testicular hormone would be to annul the 

 resistances and forces that oppose descent; in other words, to develop the vas 

 deferens, spermatic cord, cremaster, and scrotum, while maintaining the 

 genital musculature at a certain degree of relaxation. 



If the endocrine secretion of the testes is insufficient or absent, the shorten- 

 ing through atrophy associated with greater contractility or tonus of the 

 accessory muscular organs will necessarily lead to ascent of the testicle. Recent 

 work in our laboratory shows that testosterone exerts an inhibitory action on 

 the contractility "in vitro" of the vasa deferentia, epididymides, seminal 

 vesicles, and prostate glands of rats and rhesus monkeys and the vasa deferentia 

 of cats.""^^ The organs of castrated animals or of those treated with estradiol 

 become more responsive to pharmacologic agents and exhibit spontaneous or 

 automatic contractions. In normal or castrated animals treated with testos- 

 terone, there is no automatism and their reactivity to drugs is much less. 

 Experiments "in vivo" corroborate these results (Martins and Valle"'"); more- 

 over, studies of the excitability of the cremaster, as investigated with chronaxy 

 methods, seem to demonstrate that, in rats, the contractility of this muscle is 

 also under the control of testosterone (Martins and Cavalcanti^**). 



All these results agree well with the conditions necessary for testicular de- 

 scent, namely the checking of muscle actions which would work against the 

 forces that are intended to draw down the testicle. For these reasons, in our 

 preceding work we have pointed out that descent through hormonal treat- 

 ment, either experimental or clinical, should result from effects, not only 

 morphological but also functional. In certain cases, particularly when the 

 effects are very rapid, we can suppose that the dominant action is the func- 

 tional one, namely that which modifies the contractility of the musculature in 

 question. Moreover, in the papers quoted above we were able to verify the 

 fact that the latency period for testosterone treatment to exert influence upon 

 the contractility of the vas deferens and seminal vesicles is relatively short, 

 in rats 42 to 72 hours. 



