INTERSTITIAL CELLS OF URODELE TESTIS 261 



and beginning enlargement to their period of maximal develop- 

 ment, they are associated with the degeneration of lobules which 

 have completed a spermatogenetic cycle; 2) that their regressive 

 changes, whether degeneration or return to a stromal cell type, 

 unless occurring before the lobules of the region regenerate (as, 

 for example, in Desmognathus) , take place invariably if they 

 become crowded between lobules of developing germ cells, or are 

 crowded to the periphery of the testis by such growth. 



Similar correlations between interstitial cells and the tubuli 

 contorti have been described for mammals, atrophic changes 

 in the tublues being accompained by hypertrophy of the intersti- 

 tial cells. Durck found hyperplasia and hypertrophy as accom- 

 paniments both of imperfect development and secondary atrophy 

 of the tubules. Such, one would infer, is the usual condition 

 in cryptorchidism; it is the normal occurrence, too, after vasec- 

 tomy or treatment with Roentgen rays. Simmonds^ finds that 

 in case of the regeneration of the tubules after this latter treat- 

 ment (which frequently fails to entirely destroy all of the germ 

 cells) the hypertrophied condition of the Leydig's cells disappears. 

 His inference was ''that maintenance of the sex characters, by 

 means of an internal secretion, is a function of both the sperma- 

 tic cells and the cells of Leydig; that under normal conditions 

 the cells of Leydig are few in number, but, after the destruction 

 of the spermatic cells, there is vicarious intervention on their 

 part, in consequence of which they undergo proliferation." It 

 is, of course, interesting to note that in cryptorchid testes, such 

 'vicarious intervention,' according to Bouin and Ancel, may be 

 insufficient, and the animals then are subnormal in secondary 

 sex attributes, sexual instinct, or development of the genital 

 tract. It may be questioned whether such interstitial cell 

 'intervention' can persist alone for any length of time after com- 

 plete atrophy and disappearance of the tubules from the testis. 

 The cells do not long persist in the urodeles after complete 

 disappearance of the lobules they surround, but, according to 

 Smimonds' interpretation, this would be because the germ cells 



9 Quoted by Biedl, page 397. 



