HEMATOLOGIC EFFECTS OF RADIATION 1075 



Jacobson (1952) obtained similar results in CFi female mice with intra- 

 venous injections of marrow from normal mice. Rekers (1948, 1950), 

 Talbot and Pinson (1951), and Talbot and Gertsner (1951) have reported 

 negative and equivocal beneficial effects on the radiation syndrome in 

 dogs and rats, respectively, after bone-marrow administration. 



The suspension of bone marrow that Lorenz and Jacobson injected 

 contained mature and immature free cells such as granulocytes and mega- 

 karyocytes as well as free and fixed macrophages, reticular cells, and 

 endothelial tissue. It seems likely that the cells injected establish as 

 scattered foci of hematopoietic tissue and produce a factor (or factors) 

 responsible for survival of the animal and that this factor is identical 

 with that postulated in the spleen-shielding, spleen-implantation, and 

 embryo-suspension experiments. Bone-marrow injection is not as effec- 

 tive as spleen shielding or spleen transplants in enhancing survival or 

 hastening recovery of hematopoietic tissue in mice exposed to 1000 r or 

 more. Since it is not known which cells in the shielded tissue or trans- 

 planted tissue (including bone marrow) are the most important in bring- 

 ing about the effect, no adequate data are available to compare adequately 

 the relative effectiveness of splenic tissue and bone marrow in enhancing 

 survival from radiation injury. 



Heterologous Transplants and Cell Suspensions. Lorenz, Congdon, and 

 Uphoff (1952) have reported evidence of the effectiveness of heterologous 

 tissue transplants on recovery from radiation injury. Within an hour 

 after exposure of mice to 900 r (LD 99 ) of total-body X irradiation, approxi- 

 mately 25 mg of freshly aspirated guinea-pig bone marrow (in buffered 

 saline) was injected intravenously into the irradiated mice. None of the 

 control irradiated mice survived, but 40 per cent of the irradiated mice 

 which received intravenous guinea-pig bone-marrow suspension survived 

 the 28-day period of observation. As mentioned previously the survival 

 of this strain of mice injected with homologous bone marrow (1.5 mg) 

 after exposure to 900 r is ca. 75 per cent. The number of animals used 

 by Lorenz, Congdon, and Uphoff (1952) in the heterologous transplant 

 experiment is too small to warrant a positive conclusion. If further 

 data corroborate these findings, proof that the factor (or factors) is 

 humoral would be available. 



It would not seem likely that heterologous bone-marrow injection could 

 seed the hematopoietic tissue with cells which, by multiplication, repopu- 

 late the tissue. If heterologous tissue is effective as suggested by Lorenz, 

 it seems more likely that this heterologous tissue lives, at least tempo- 

 rarily, in its new environment and produces a noncellular substance (or 

 substances) that aids in recovery from the radiation injury. 



Po stir radiation Parabiosis. Barnes and Furth (1943) first demon- 

 strated that parabiosis diminished the deleterious effects of irradiation. 

 When one member of a parabiotic pair was irradiated, the pathological 



