[Female sex hormones and thrombocytopoiesis]

The influence of estradiol, estriol and progesterone was studied on basic parameters of thrombocytopoiesis and thrombocytopoietic activity of plasmas of female rats. It was established that the investigated hormones increased highly the number of thrombocytes, the percentage of 75-selenomethionine incorporated in newly formed thrombocytes and the total number of megakaryocytes. Thrombocytopoietic activity of the plasma was raised considerably only in rats, injected with estradiol, but the remaining hormones did not induce significant changes in this activity. It is accepted that estradiol, estriol and progesterone stimulate thrombocytopoiesis of female rats by various mechanisms. Estradiol increases highly the formation of specific humoral regulator of thrombocytopoiesis--throbocytopoietin. The stimulating effect of estriol and progesterone is most probably nonspecific (thrombocytopoietin-independent), as the first hormone activates proliferation of megakaryocytes greatly, but the second hormone-the differentiation of these cells.