Abstract
Polycythemic x-irradiated female mice, injected with 12-day fetal liver cells, showed 81% suppression of erythroid spleen colonies as compared with nonpolycythemic recipients. On the other hand, in male recipients only 16% suppression was observed. Hence, androgenic hormones seem to play a role in regulating erythropoiesis of explanted fetal stem cells. To test this, we examined the effect of testosterone injected into polycythemic female recipients on the production of erythroid colonies from fetal liver cells. Testosterone was found to alleviate the suppressive effect of polycythemia. Antierythropoietin prevented the appearance of erythroid colonies in testosterone-treated animals. Thus, testosterone seems to act by increasing the levels of, or susceptibility to erythropoietin. Under similar conditions, testosterone did not trigger the formation of erythroid colonies from bone marrow cells in polycythemic recipients. Hence, fetal cells can be induced to form erythroid colonies by doses of erythropoietin that are too low to induce erythroid colonies in bone marrow cells.
