394 INTERNAL SECRETION 



dymis (tumours, inflammation leading to atrophy of the vas 

 deferens) do not inhibit sexual instinct nor do they affect the 

 male secondary traits. 



These observations prove that the internal secretory function 

 of the testis does not lie in the generative elements. The question 

 which now arises is, in which of the two remaining elements, 

 Sertoli's cells or the cells of Leydig, is this function lodged. In 

 the hope of solving this problem, Bouin and Ancel endeavoured 

 by experimental measures to separate the functions of these two 

 groups of cells. Their course of reasoning was as follows. The 

 testicle resembles the other paired glands in that the removal of 

 one gland provokes compensatory hypertrophy of the other unit 

 of the pair. This hypertrophy presumably affects both the in- 

 ternal and external secretory tissue equally. If, however, the vas 

 deferens of the testicle left in situ is ligatured, the semen-forming 

 parts will be entirely destroyed while the hormone-forming tissue 

 of the second gland will remain uninjured; such being the case, 

 the compensatory hypertrophy will be expressed in those cells 

 only the function of which is increased. Experiments with rab- 

 bits showed that, about six months after operation (unilateral 

 castration, ligature of the vas deferens of the other side), the 

 testicle left in situ appeared to be very much smaller, the semi- 

 niferous tubules contained a few spermatogoniae, and Sertoli's 

 cells were unchanged ; while the interstitial gland was enormously 

 developed and showed signs of secretory hyperactivity. At the 

 end of ten to twelve months the seminiferous tubules had become 

 very much shrivelled, Sertoli's cells were degenerated, and the 

 entire testis was almost exclusively composed of extremely hyper- 

 plastic cells of Leydig. 



Tournade showed further that, in the case of rats, long- 

 continued ligature of the vas deferens leads ultimately to degenera- 

 tive destruction of Sertoli's cells. 



Similar results were observed in tjie case of pigs with uni- 

 lateral cryptorchidism, from which the second normal testicle had 

 been removed before the age of sexual maturity. There was 

 complete absence of spermatogenesis and, in many instances, the 

 cryptorchidic testicle showed more or less marked hypertrophy, 

 the weight sometimes reaching double the normal. This hyper- 

 trophy was due to development of Leydig's cells, while Sertoli's 

 cells in the seminiferous tubules were unchanged. In three 

 rryptorchidic pigs, Bouin and Ancel found that the testicles had 

 remained at a primitive stage of development, Sertoli's cells being 

 absent, but Leydig's cells well developed. These animals were 

 typically male in appearance and the genital tract was fully 

 developed. 



It is evident, then, that the presence or absence of Sertoli's 

 cells does not affect the secondary sex characters, and that the 

 internal secretory function is the sole property of the interstitial 



