SEASONAL MODIFICATIONS IN TESTES OF VERTEBRATES 



z6 7 



by changes in feathering. The period 

 between the disappearance of interstitial 

 cells and the onset of sexual activity is so 

 long that it seems improbable that the 

 interstitial cells had any relation to sex 

 desire and mating behavior. 



It must be admitted that the methods of 

 determining quantitative amounts of in- 

 terstitial cells have not been accurate. 

 This has been pointed out by Bascom (4). 

 The authors have offered them as relative 

 quantities and in such a sense they have 

 shown the gross changes met with. One 

 error is present throughout the early work 

 that might explain some of the minor 

 discrepancies seen in the various reports; 

 namely the failure to distinguish between 

 intertubular and interstitial tissue. Nor 

 is this error corrected by the use of 

 Bascom's method. It is difficult to make 

 sure of estimating an increase in inter- 

 stitial cell quantity and number in any 

 way short of actually measuring and 

 counting the individual cells. But careful 

 quantitative estimations of interstitial 

 cell increases do not appear necessary. 

 According to Lipschutz (41) one-sixteenth 

 of a testis produces enough hormone to 

 keep the animal normal. It is also known 

 that the testicular grafts will promote the 

 normal development of male rats, guinea 

 pigs, or birds. Small variations are 

 therefore not important. 



Are there cytoplasmic or nuclear 

 changes paralleling the periods of sex 

 activity that might indicate which cells 

 secrete the testicular hormone? The 

 change from fibroblast to interstitial cell 

 is marked by the appearance of fuchsino- 

 phile granules in the cytoplasm and the 

 inclusion of much fat. But this occurs 

 during the post-active period according 

 to the data reviewed above. Benoit 

 found that the interstitial cells of Cam- 

 basson decrease in quantity during the 

 season of sex activity, but he believes that 



they become more glandular at this time. 

 They contain voluminous spherules which 

 produce a fuchsinophile secretion. The 

 supporters of the interstitial cell secretory 

 theory, after noting what they thought was 

 a parallelism between sex activity and 

 interstitial cell increase, postulated that 

 these cytoplasmic inclusions were the 

 hormone products being formed in the 

 cells. No proof has been offered in sup- 

 port of this supposition. Now Benoit 

 and others turn about and postulate that 

 since certain cells contain fuchsinophile 

 granules they must be secretory cells. 

 They must first prove that such granules 

 are hormonal products within the cell 

 before they can argue that cells containing 

 such granules are secretory cells. Parhon 

 and Parhon noted that the interstitial cells 

 in the goose become charged with fat 

 granules, which they believed to be 

 secretory material, but this occurs in the 

 fall after mating has ceased. Champy 

 found changes in the interstitial cells and 

 in the Sertoli cells that indicated transfer 

 of fat inclusions from the former to the 

 latter. He concluded that the phosphorus 

 fat elaborated by the interstitial cells 

 serves as nutrition for the spermatozoa 

 being formed in this tissue. He then 

 postulates that in some mysterious manner 

 the interstitial cells determine the develop- 

 ment of the germ cell, presumably through 

 the transfer of this secretory (fatty) 

 material. Humphrey has very clearly 

 shown that interstitial cell increase is 

 related to emptying of spermatic tubules 

 and that it is not a seasonal condition. 

 Humphrey suggests that they may serve 

 as a nutritional balance in the testis and 

 also prevent a sudden collapse of the 

 lobules and of the testis when sperm are 

 ejected. Oslund (2.8) suggests that they 

 are more strictly a result and ascribes to 

 them no functional purpose. 

 The writer interprets Champy as stating 



