C-type virus particle formation in erythroblastic islands in spleens of C3Hf mice injected with erythropoietin.

Previous studies suggested a possible association between C-type virus particle formation and erythropoiesis. In this experiment, normal C3Hf mice were injected with erythropoietin in order to increase the rate of erythropoiesis. Sections of spleen from these animals revealed extensive areas of erythroblasts. C-type particles, budding from erythroblasts, were often observed in such areas of spleen from every mouse injected with erythropoietin. In contrast, in sections of spleen from control mice, zones of erythropoiesis were limited, and only a few scattered C-type virus particles were observed in some of the animals examined.