156 



Discussion 



mouse erythrocytes by rat erythrocytes occurs. These results also 

 demonstrate that the injected rat bone marrow has survived and pro- 

 liferates in the irradiated mice. Results of a similar nature have been 

 reported by Lindsley, Odell and Tausche (1955, Proc. Soc. exp. Biol., 

 N.Y., 90, 512) in the case of homologous bone marrow injection into 

 irradiated rats, although in these experiments no significant effect of the 

 bone marrow on survival was observed. 



ANTI 



RAT 



SERUM 



43+- 



2-f- - 



M 



< 



SB 

 l-l 



n 



3 



o 

 a 



< 



ANTI 



MOUSE 



SERUM 



o o 



o o 

 o 



OOP 



y/- 



2 + - 



3-1- 



r 

 o 



-T— 

 10 



-I— //- 



20 30 



50 



— I— 

 70 



— I— 

 90 



—1 — 

 110 



DAYS A?TEH 

 IHRADIATIOl 



Fig. 3. (Van Bekkum). Identification of erythrocytes in irradiated and rat 



bone marrow treated mice. 



In our third approach a histochemical method was used which 

 permits differentiation between rat and mouse granulocytes. Wachstein 

 (1946, J. Lab. din. Med., 31, 1) observed that rat granulocytes show a 

 strongly positive alkaline phosphatase reaction while mouse granulo- 

 cytes are consistently negative in this respect. Irradiated mice were 

 injected with rat bone marrow and on various days after the irradiation 

 smears of the peripheral blood were prepared and studied with the 

 alkaline phosphatase reaction. Table III shows the percentage of posi- 

 tive granulocytes in irradiated mice after treatment with rat bone 

 marrow. In most cases the granulocytes were predominantly identified 

 as rat cells. It should be noted that No well. Cole and Habermeyer 

 (1955, USNRDL report T. R. 59) have independently obtained iden- 

 tical results using Wachstein' s method. 



Finally, I want to comment on the survival of irradiated mice after 

 treatment with homologous and heterologous bone marrow. As shown 



