SEASONAL MODIFICATIONS IN TESTES OF VERTEBRATES 



z6 3 



divide less actively. The tubule cells are 

 at this time charged with fat granules. 

 The intertubular tissue is more developed 

 than in spring, and the interstitial cells, 

 like the tubule cells, are charged with 

 fat granules. This condition resembles 

 that reported by Champy for Amphibia. 



Benoit (5 and 6) states that during the 

 winter while the testis (of Cambasson) is 

 in repose it contains spermatogonia and 

 Sertoli cells. At the beginning of the 

 sexual period in spring the seminiferous 

 tubules enlarge a little. They slowly 

 gain in volume as spermatogenesis in- 

 creases. During the early period of 

 development spermatocytes make their 

 appearance, and then later spermatids are 

 found. Only when Cambasson is fully 

 active sexually are spermatozoa present, 

 and at this time the testis is maximum in 

 size. 



He states that interstitial cells are very 

 abundant during winter, when spermato- 

 genesis has ceased. They then contain 

 fat granules. Toward spring many con- 

 nective tissue cells become enlarged. 

 Some contain fuchsinophile spherules. 

 When sex activity is at its height these 

 interstitial cells are relatively much less 

 abundant than during winter and early 

 spring. They change in cytological 

 structure, becoming, he thinks, glandular. 

 He finds no volumetric parallelism be- 

 tween the interstitial cells and sex activity 

 and endeavors to find a parallelism in the 

 cytological changes seen at this time. 

 These cytological modifications were 

 briefly pointed out by Parhon and Parhon, 

 but these authors were not led to believe 

 that these cells were more secretory during 

 the period of sex activity than during the 

 inactive period. Many investigators are 

 inclined to look upon these changes as 

 showing that the interstitial cells are 

 trophic bodies for the tubule cells. See 

 Saintmont (33) and Tandler and Grosz 



(34). Others view them as consequences 

 of changes in size of the tubules rather 

 than from a teleological aspect. See 

 Whitehead (40), Kuntz (m)> Humphrey 

 (zi), and Oslund (z8). 



It is quite evident that sex activity in 

 birds is pronounced during the period of 

 spermatogenesis. At that time the testes 

 are enlarged as compared with the inactive 

 period. On the other hand there is an 

 increase in the number and volume of 

 interstitial cells during the period of sexual 

 /^activity. Plumage is usually more 

 brilliant during the time that spermato- 

 genesis is most active and is dull following 

 the autumnal molt, when the interstitial 

 cells are abundant. The parallelism be- 

 tween spermatogenesis and sexual activity 

 is evident, while there is an inverse re- 

 lationship between sexual activity and 

 interstitial cells. 



MODIFICATIONS IN TESTES OF MAMMALS 



In testes of mammals the germinal 

 epithelium is found in seminiferous tu- 

 bules. Spermatogenesis proceeds in 

 waves, and all of its stages may be found 

 in each tubule. Between the tubules are 

 found nerve elements, blood and lymph 

 vessels, and connective tissue cells. Some 

 of the connective tissue cells are typical 

 fibroblasts, while others are large and 

 contain an abundance of cytoplasm with 

 fuchsinophile granules. It should be em- 

 phasized that not all connective tissue 

 cells are interstitial cells, nor is the 

 intertubular space always filled with in- 

 terstitial cells nor even with fibroblasts. 

 It often contains much lymph and always 

 has blood and lymph vessels and nerve 

 elements. Of all the intertubular tissue 

 only the interstitial cells are supposed to 

 elaborate a glandular product. 



Hansemann (19) reported that in the 

 Marmot (Marmot a marmot a) there is no 

 trace of spermatogenesis during hiberna- 





