IRRADIATION AND RLPLACEMENT OF BONE MARROW L'SlNCi '"^Au 



Histo-pathology 



Findings reported under this heading are based on biopsies taken from 

 two normal rablnts not irradiated or treated in any way, one raljbit which 

 had been intravenously injected with of the order of 50 mg of stable collcjidal 

 gold and 11 of the rabbits of series b and c which had succumbed. So far 

 no survivors have been sacrificed. 



While rabbits examined, including some receiving higher specific curie 

 doses than those shown in Table 4, have received /3 doses to the liver of up to 

 13,000 REP and spleen doses of up to 5000 REP, no biopsy has revealed 

 any damage to liver or spleen which could be attributed to radiation. 



Examination of bone-marrow biopsies has sho\\n severe hypoplasia or 

 complete aplasia in all cases except Nos. 2c and 4c (treated rabbits 

 ^\•hich received 5700 and 2700 REP respectively to the bone marrow), 

 wliich showed moderate to severe hypoplasia. No significant correlation 

 was observed between the degree of hypoplasia and the roentgen dose 

 received by the marrow, although one of the two rabbits with complete 

 aplasia, No. 7b, a control, received the highest ^ dose, that is 22,000 REP. 



In some of these cases there were small foci in the bone marrow adipose 

 tissue resembling necrosis. This could not be differentiated with confidence 

 from post-mortem autolysis. 



In some there were small foci of residual haemopoietic tissue. Whether 

 this ^vas associated \vith, or due to, severe hypoplasia, or to implantation 

 from the transfused bone marrow, it is not possible to say at the present stage 

 of the investigation. 



Gross appearance at autopsy 



Findings reported under this heading are based on examination of all 19 

 rabbits which have died. 



These findings are characterized chiefly by petechial haemmorrhage, 

 although in some cases, notably those surviving four or five days only, no 

 petechial haemorrhage was observed. In only one non-splenectomized case. 

 No. 5d, a control, was the degree of haemorrhage believed sufficient to 

 have caused death. But in both splenectomized cases there was gross 

 haemorrhage on heart, lungs and intestines and in skeletal muscle. 



In some cases liver, lungs and bone marrow were pale, and in some the 

 marrow was hyperaemic and sloppy. Gross effects did not appear to be 

 related to presence or absence of treatment. 



Weight loss to time of death in 1 1 rabbits which received 2-5 to 3-0 

 mC/kg of ^^^Au ranged from 1-5 to 14-8 per cent, with mean 8-5 per cent 

 and standard deviation ±4-6 per cent. 



Haematology 



In general, the picture for the total leukocyte count was characterized by 

 an initial sharp fall to a minimum in from two to six days, followed by a 

 gradual recovery to near normal in about three weeks for survivors, or a 

 plateau at the minimum value for non-survivors. For rabbits which received 

 only the single bone-marrow transfusion at seven or eight days there was no 

 significant difference, during the life-time of the non-survivors, between 

 the counts for controls and treated rabbits. But for rabbits which received 



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