INTERNAL SECRETION OF TESTICLE 143 



of the tubules (quoted from Sand, 1921 c). Some investigators 

 especially Kyrle, mention also an hypertrophy of the inter- 

 stitial cells. Very detailed investigations on this question 

 have been made by Sand (1918, p. 109; 1921 c), who caused in 

 rabbits, guinea pigs and rats retention of both testicles by 

 loosening the testicle from the gubernaculum and closing the 

 processus vaginalis. He observed a degeneration of the semini- 

 ferous tubules and an hypertrophy of the interstitial cells; 

 there were no signs of castration. 



Crew (1922), suggested that the degenerative changes 

 occurring in the undescended testicle are due to the differ- 

 ence of temperature in the scrotum and the abdominal cavity. 

 The testis is adapted to the lower temperature of the scrotal 

 sac ; the temperature of the abdominal cavity (the difference 

 is of several degrees) is not that at which the final stages 

 of spermatogenesis normally develop. 



The observations made on men and animals with retained 

 testicles show with complete certainty that full development 

 of sexual characters is possible without spermatogenesis 

 proceeding to production of spermatozoa. 



Ancel and Bouin (1904 b) further record an observation made 

 on a pig killed at an age of six months with normally developed 

 sexual characters, in which animal in the retained testicles even 

 the cells of SertoH were absent. So one may suppose that the 

 internal secretion of the retained testicle is produced only by 

 the interstitial cells. This was already suggested in 190 1 by 

 Regaud and Policard (1901). Detailed investigations on this 

 question were made by Bouin and Ancel on pigs, in which 

 retention of testicles is very frequent. The degree of develop- 

 ment of the genital organs in pigs with retained testicles is 

 very variable. According to Ancel and Bouin (1904 g) the 

 interstitial tissue in the retained testicle of the pig is the better 

 developed the greater the weight of the testicle, and there 

 is, as already mentioned, a proportional relation between 

 the quantity of the interstitial cells and the degree of develop- 

 ment of the genital apparatus. It is clear that such a quantita- 

 tive statement is of the greatest importance in relation to the 

 question of the endocrine function of the interstitial cells, and 

 it was these most important observations of Bouin and Ancel 

 which first led me to plan out quantitative investigations on 

 the internal secretion of the testicle. As a result of our 



