Abstract
The effect of sex hormones on the thrombocytopoietic function was studied in rabbits with a view to clarification of the cause of thrombocytopenia observed in the preceding study during pregnancy and after progesterone therapy in threatened abortion.
1) The rate of megakaryocytic platelet formation in the bone marrow decreased by 0 to 60 per cent after administration of estrogen (Es) and/or progesterone (Pr), as compared to the pretreatment level.
2) Administration of Es was noted to be followed by a decrease in the number of megacaryocytes in the bone marrow while the effect of Pr was obscure.
3) A marked diminution of platelet count of the peripheral blood occurred after ad-ministration of Es and Pr in combination. With either hormone given alone, nevertheless, no constant trend of change in the peripheral platelet count was observed to exist.
The findings for platelet counts and clot retraction rates obtained in the pregnant and inr the parturient in these clinical studies thus determine a part of the cause of maternal thrombocytopenia.
