INTERNAL SECRETION OF TESTICLE 177 



brought about by testicular tissue where the tubules are in 

 an infantile stage, but where the interstitial cells are of the 

 adult type. But if we consider the state of the testicle or of 

 the testicular fragment in these cases from a dynamical point 

 of view, together with all the resulting processes, it is difficult 

 to avoid the conclusion that spermatogenesis is possibly in- 

 volved in the puberal development of the interstitial cells, and 

 so is indirectly involved in the internal secretion of the testicle. 

 Spermatogenesis proceeding to a certain degree may be neces- 

 sary for the transformation of the quiescent form of the 

 interstitial cells into the puberal form. Our knowledge, 

 however, of the time relations between spermatogenesis and 

 puberal development of the interstitial cells is at present 

 incomplete. 



There is a further consideration of a more general character 

 which supports such a theory. As we shall see in Chapter V., 

 it is almost unanimously agreed that the follicle is an endocrine 

 apparatus in the ovary. Folhcular development is connected 

 with development of the ovum. But the ovum itself is not 

 necessary for the production of the internal secretion of the 

 follicle, as is shown by the fact that the follicle or the corpus 

 luteum which persists after the death or the exodus of the ovum, 

 continues to elaborate internal secretions. Cells (of epithelial 

 or connective tissue origin) hitherto not involved in internal 

 secretion are transformed into endocrine cells during the process 

 of ripening of the germinative cells of the ovary. The same is 

 possibly true for the testicle. So the theory suggested above 

 has its analogy in what is known in regard to the ovary. The 

 term "follicular theory" may be conveniently used in this 

 connection. 



Such a follicular theory of the endocrine function of the 

 testicle cannot be based on proof, at any rate at present. 

 Nevertheless it may serve as a convenient working 

 hypothesis. 



The assumption of Berblinger (1921), that the interstitial 

 cells serve for the storing of hormones produced by spermatic 

 cells, seems to me unjustified by the facts described in this 

 chapter. 



