NEUTRON EFFECTS ON ANIMALS 179 



tubules the nuclei were uniform in appearance, showed no mitosis and were 

 arranged peripherally in the basement zone. Other tubules were normal 

 in size and cellular structure although the presence of spermatogenesis was 

 questionable. These were in sharp contrast to atrophied tubules in close 

 proximity. Intermediate stages of disintegration were present and were 

 characterized by nuclear pycnosis and vacuolization of the germinal epi- 

 thelium. The interstitital cells were normal and there was a small amount 

 of interstitial edema. 



16th Day. Damage was characterized by atrophied tubules (Fig. 15) 

 consisting primarily of Sertoli cells and homogeneous pale red-staining 

 material. A few large multinucleated cells were scattered throughout the 



tubules. 



24th Day. The pathological changes were similar to those of the 16th 

 day, although the cellular debris w^as less in amount. 



32nd Day. The interstitial cells were prominent and a large amount of 

 fluid was present in the mterstitial spaces. The tubules were uniformly 

 shrunken and consisted of SertoU cells, red-staining syncytium and sperma- 

 togonia . 



32nd to 100th Day. ^'ery little change occurred during this period. 

 Profound atrophy of the tubules, edema and aspermia were characteristic. 

 (Typical section. 60th day. Fig. 16.) 



120th Day. Degeneration of tubular elements was so profound that 

 no recognizable germinal epithelium could be found. The tubules con- 

 sisted only of pale red-staining reticulum and Sertoli cells. Interstitial 

 cells were prominent and appeared normal. Very little difference could 

 be found between these testes and those studied after 150 days. For the 

 first time since irradiation at this dose, some regeneration occurred. The 

 tubules were small and consisted only of Sertoli cells as has been noted 

 before. However, a few tubules regenerated to the extent of producing a 

 few spermatids. Structures that resembled sperm heads were present. 

 No complete spermatogenesis was found and there was an abundance of 

 interstitial edema. 



355 n. No histopathological changes Avere found during the 1st day. 



2nd Day. INIany cells, apparently spermatocytes, had become detached 

 in the disorganized tissue and stained darkly. The other tissue elements 

 appeared normal. 



3rd Day. The remaining animals had died and were not examined. 



C. Fertilily Tests. In order to compare the histological injury in the 

 testes with the functional ability, male rats of approximately the same size, 

 which had received 11.3, 56.4 or 113 n, were mated at intervals with normal 

 non-irradiated females of reproductive age. Each male was placed AAnth 

 2 females for each test period of 7 to 9 days. Eight to 10 days after separa- 



