THE EFFECT OF RADIATION ON FROZEN TUMOUR CELLS 



indication that freezing alone does not impair their viabihty. Figure 2 

 shows the percentage take of fresh irradiated and control grafts. The 

 appearance of tumours derived from irradiated grafts is delayed for one 



700 



(Frozen) 



100 



(Fresh) 



Gamma rajs 

 (Fresh) 



2 3 



Time in weelis 



Figure 1. Percentage take of frozen and 

 fresh unirradiated grafts {gamma ray 

 experiment) 



12 3 1 



Time in wee/<s 



Figure 2. Percentage take of fresh irradiated 



{gamma rays) ■ and fresh 



control grafts 



week as compared with the unirradiated controls ; two weeks after inocula- 

 tion it is 34 per cent ; at four weeks it is 56 per cent. Figure 3 gives the 

 results obtained with frozen irradiated grafts. In contrast to the fresh 



100 



80 



\ 



60 



I 



W 



20 



Gamma ra^'S (Frozen) 



Gamma rajs 

 [Frozen) 



I 

 I 



11 

 I 

 I 



; 2 3 



Time in tveeks 



Figure 3. Percentage take of frozen irra- 

 diated {gamma rays) and frozen 



control grafts 



f 2 3 



Time in weel<s 



Figure 4. Comparison of the inhibition of 

 tumour takes from irradiated {gamma 

 rays) fresh and frozen grafts expressed 

 as the difference from the control per- 

 centage take 



irradiated cells the first appearance of tumours is delayed longer and the 

 percentage take is significantly smaller. At three weeks after grafting it is 

 24 per cent and at four weeks 3 1 per cent. Figure 4 gives a direct comparison 



322 



