DISCUSSION 



varied according to the normal patterns seen in the various eones. In the reticularis, 

 pyknosis was the rule ; in the fasciculata, either pyknosis or a loss of basophilia and 

 'fading' ; in the reticularis, a breaking up of the nucleus, the stroma disappearing 

 and leaving the chromatin particles scattered. 



In animals dying in the first few days after irradiation, hyperaemia in the zona 

 reticularis was common. As in the I'abbit no evidence of an inflammatory reaction 

 was seen at any time. Mitosis was in general absent but a few mitotic figures were 

 seen in two rats dying on the 29th and 31st days. They were all in the outer part 

 of the zona fasciculata. 



In neither species was there any unequivocal evidence of the eflFect of Synkavit. 

 In the rat, however, the general impression was one of greater damage in those 

 receiving the compound than in the controls. 



SUMMARY 



(7) In rabbits the administration of Synkavit prior and after irradiation has shown 

 slight increase in tolerance of irradiation, and although the difference in the mortality 

 rate of rabbits and rats is not significant, the weight curve and the well-being of the 

 animals suggested an increased tolerance of radiation in this species. In rats an 

 opposite effect was found (Mitchell*, 1951 ; JoLLEsf, 1952). The histological 

 changes in the adrenals stained only with haematoxylin and eosin can clearly give 

 no more than a hint of the changes which take place in the irradiated animals. 

 Nevertheless, enough has been found to suggest that a more detailed study of adrenal 

 pathology and function might be fruitful in elucidating the mechanism of radiation 

 effects. 



(2) The histological findings of the effects of Synkavit were disappointing, but as 

 the main demonstrable effect of this compound is mitotic inhibition (Mitchell J, 

 1949), it is perhaps not surprising that the histological appearance of tissue already 

 showing nuclear damage and mitotic arrest from the effect of the X-rays, should be 

 little altered by the chemical. Nevertheless the suggestion of greater damage in the 

 adrenals of rats receiving Synkavit makes it possible that this may at least have contri- 

 buted to the deleterious effect of this compound in this species. 



Although it is hazardous to generalize from the described experiments the fact 

 that patients suffering from malignant tumours who receive daily injections of 

 Synkavit while undergoing radiotherapy stand treatment better, induces one to 

 venture an opinion that the administration of this compound in humans produces a 

 response similar to that found in rabbits rather than that in rats. In this context 

 however it has to be borne in mind that a selective concentration of the drug in 

 tumours has been shown by Mitchell by means of ultra-violet microphotography 

 and that the use of Synkavit in normal individuals probably produces effects different 

 from those to be expected in tumour-bearing patients receiving treatment to a part 

 of the body only. 



* Mitchell, J. S. Brit. Empire Cancer Camp. 29th Ann. Rep. London, 1951, p. 192. 



I JoLLES, B. Brit. Empire Cancer Camp. 30th Arm. Rep. London, 1952, p. 325. 



X Mitchell, J. S. Brit. Empire Cancer Camp. 27th Ann. Rep. London, 1949, p. 214. 



193 



