122 INTERNAL SECRETIONS 



would be of the same mesothelial origin and in a relation 

 similar to that of nerve cells and neuroglia cells." 



To the question whether the interstitial cells originate from 

 mesenchyme, or from other primitive tissue giving origin to 

 epithelium, great importance has been attached by some 

 authors. They think that by demonstrating that the inter- 

 stitial cells are derived from mesenchyme, and have the 

 character of connective tissue cells, it is proved that these 

 cells cannot have a glandular function. But I think that no 

 conclusion concerning the function of the interstitial cells can 

 be drawn from the embryological data. First of all, the 

 mesenchyme is a part of the mesoderm. Secondly, as was 

 mentioned above, it is possible that the connective tissue cells, 

 which after birth may be transformed into interstitial cells, are 

 not common connective cells, but a peculiar type of epitheUal 

 origin. Thirdly, even if the interstitial were really identical 

 with common connective tissue cells, this would not preclude 

 the possibility of their being glandular cells. On the contrary 

 as we have shown above, there is little doubt that the inter- 

 stitial cells histologically are glandular elements. After all, it 

 seems to me undesirable, when discussing the question as to 

 which part of the testicle produces the internal secretion, to 

 attach much weight to evidence as to the origin of these cells. 

 The question as to the functions of the different parts of the 

 testicle can be decided only by experiment, which may be 

 supplemented by pathological observation. 



It has been demonstrated by various workers that the 

 interstitial tissue has a different appearance at different ages. 

 Bouin and Ancel (1904 a, f) showed in the horse that the 

 interstitial tissue present in the embryonic testicle diminishes 

 in the later stages of intrauterine hfe, and that the formation 

 of a new interstitial tissue begins after birth, to be completed 

 when spermatogenesis commences. Similar observations have 

 been recently made by Aron (1921) on the pig and the 

 sheep. According to Aron, the interstitial cells formed after 

 birth, have a different cytological appearance from those 

 present during intrauterine life. As regards rabbits and guinea 

 pigs, some observations have been made in our Institute by 

 Dr. Wagner. The figures 57 and 58 show in a very striking 

 way the gradual transformation of the tissue between the 

 tubules in the testicle of the guinea pig into cords of 



