E. H. BETZ 



Recently Selye^i ^^s shown that somatotrophic hormone is able to 

 counteract the catabolic effect of protein which normally occurs after a 

 stress or an injection of cortisone. On the other hand, it is known that the 

 production and differentiation of blood cells is closely related with the 

 protein metabolism. Therefore, we studied the effect of somatotrophic 

 hormone on the haematopoietic regeneration of irradiated rats. We com- 

 pared the results with thoic obtained by using other substances such as 

 testosterone propionate and vitamin Bj., whose effect on protein anabolism 

 is also well known. 



(5) Influence of somatotrophic hormone on the haematopoietic regeneration 



Methods : Three groups of rats were studied, all irradiated with a lethal dose of 

 X-rays (800 r) . The first group is used as control. The animals of the second group 

 are irradiated and injected daily with 5I.U. of growth hormone. The rats of the 



Figure 3. Femoral bone marrow of tlie rat. 10 days after 800 r .• almost no 

 regeneration of t/ie marrow has taken place {200 X ) 



third group are adrenalectomized before the irradiation. Afterwards, they are 

 injected daily with 2-5mg of cortisone and 5I.U. of growth hormone. The 

 haematopoietic tissues are studied histologically. 



In the control group, all the animals died within the eleven days following 

 the irradiation, without showing any sign of haematopoietic regeneration. 

 The rats irradiated and injected with growth hormone behaved like the 

 controls ; they died between the fourth and the tenth day without regenera- 

 tion of their haematopoietic tissues. The adrenalectomized rats injected with 

 costerone and somatotrophic hormone proved more resistant to a lethal dose 

 of X-rays ; about 25 per cent of the individuals of this group survived, showing 

 an extensive regeneration of lymph nodes, spleen and bone marrow. In the 

 bone marrow and spleen, the differences between control rats and treated 

 rats are striking. In the control rats, the bone marrow is congested and 

 oedematous; the myeloid cells have almost all disappeared ; the spleen is 



295 



