Effect of estradiol on erythropoiesis and megakaryocytopoiesis in mice.

The effect of four 1.0-mg estradiol benzoate injections on hemopoiesis in the spleen and bone marrow in mice was studied. The number, concentration and mitotic activity of megakaryocytes (MKC) and number of MKC colonies in the spleen were found to be increased one and two weeks after cessation of the estradiol injections. MKC concentration in the bone marrow rose during the experimental period. The MKC increased in number during the first week after estradiol, but dropped to normal after the second week. The number and mitotic activity of erythroid precursors increased in the bone marrow and spleen three days after the cessation of estradiol injections. These findings suggest that estrogen enhances megakaryocytopoiesis and erythropoiesis in the bone marrow and spleen in mice.