[Properties of eeythropoietin-independent mouse bone marrow precursor cells of the erythroid series]. / Svoistva éritropoétinnezavisimykh kletok-predshestvennikov éritroidnogo riada kostnogo mozga myshei.

The properties of early (BFUen) and late (CFUen) erythropoietin-independent progenitors were studied in bone marrow plasma clot cultures of mice. Syngeneic serum was used as a stimulant of colony formation. It was revealed that serum from polycytemic mice did not alter the efficacy of cloning the erythroid progenitors. Varying effects produced on erythropoiesis in vivo did not significantly change the number of CFUen and BFUen, with the exception of posttransfusion polycytemia where the number of CFUen showed a statistically significant rise. Assessment of radiosensitivity and proliferative activity of the erythroid progenitors showed that for CFUen Do=206 rad and n=1.3; for BFUen Do=118 rad and n=1.4; the proportion of proliferating CFUen was 42% +/- 12.5 and that of BFUen 46% +/- 4.5. The data obtained confirm the hypothesis of the erythropoietin-independent nature of the erythroid progenitors expressed under the culture conditions used.

[Erythroid precursors studied by mouse bone marrow cultivation in a plasma clot]. / Issledovanie éritroidnykh predshestvennikov metodom kul'tivirovaniia kostnogo mozga myshei v plazmennom sgutke.

Two types of erythroid precursors were found by cultivation of the mouse bone marrow in the plasma clot with mouse serum and without adding exogenic erythropoietin to the culture medium. The first precursor had properties similar to the erythroid colony-forming unit (CFUe) previously described while the second resembles in its properties the erythroid burst-forming unit (BFUe). Optimal concentration of mouse serum in the culture medium was 10-15%. Clone nature of the colonies and bursts described is confirmed by linear dependence of their number on the cell concentration in the culture.

[Mechanism of inhibition of erythropoiesis during post-transfusion polycythemia]. / O mekhanizme ugneteniia éritropoeza pri posttransfuzionnoi politsimij

In mouse with posttransfusion polycytemia, depression of erythropoiesis suggests that, in response to erythrocytes transfusion, not only the differentiation of erythropoietin-sensitive cells is interrupted (cessation of inflow of the labelled erythrocytes into the circulation on the 8th day), but the proligeration of differentiated erythroid precursors is also inhibited (fall of amount of labelled erythrocytes during first days). This was corroborated by analysis of the experimental data with the aid of mathematical model of erythropoiesis. The model revealed that, in posttransfusion polycytemia, division of 40 percent of all divisionable erythroid precursors was halted.