Studies on medullary and extramedullary erythropoiesis in the adult mouse.

BOZZINI, C. E., M. E. BARRIO RENDO, F. C. H. DEVOTO, AND C. E. EPPER. Studies on medullary and extramedullary erythropoiesis in the adult mouse. Am. J. Physiol. 219(3) : 724-728. 1970.Splenic and marrow erythropoiesis was compared in the mouse following stimulation by hypoxia, bleeding, or injections of erythropoietin or depression of erythropoiesis by transfusion. The effect of splenectomy on both total circulating red cell volume and erythroid response to hypoxia or erythropoietin administration was also determined. It was found that bone marrow erythropoiesis is almost twice splenic erythropoiesis in the normal CFW/ep mouse. The fractional depression of 5gFe uptake produced by transfusion was more marked in the spleen than in bone marrow. Bleeding or exposure to hypoxia produced a marked increase in splenic radioiron incorporation. Radioiron uptake by the bone marrow was not affected. The number of nucleated erythroid precursors in femoral marrow was not affected by bleeding. Splenectomy produced a mild anemia, total red cell mass being decreased by 15%. Red cell production was observed in both liver and axillary lymph nodes in splenectomized mice exposed to hypoxia. These data strongly suggest that red cell production in bone marrow is not sufficient in the adult mouse to meet the normal demand for erythrocytes, and, therefore, requires the assistance of extramedullary erythropoiesis.