الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Megakaryopoiesis or thrombopoiesis is a complex multi-step process that begins with the commitment of a pluripotent haematopoietic stem cells to a differentiation pathway ( Ellis, et al., 1995 ). The committed megakaryocyte progenitor cell undergoes proliferation and subsequent differentiation into a mature megkarycyte which ultimately releases platelets into the circulation ( Mazur, 1987 ). Thrombopoiesis is regulated by a immoral mechanism in which the rate of platelet production responds to the number or mass of circulating platelets ( Odell 1974 and Ebbe 1976 ). Several cytokines such as interleukin-3, interLukin-6, interleukin-11, leukaemia inhibitory factor and granulocyte-macrophage colony stimulating factors have shown to promote megakaryocytopoiesis at different stages of develoyment and platelet production ( Yang, et al., 1986 Ikebuchi, et al., 1987; Qiesenbery, et al., 1985; Bruno, et al., 1989; Ishibasli, et al., 1989; Hill, et al., 1990; Teramura, et al., 1992; Burstein, et al., 1992; Metcalf, et al., 1991 and Wong, et al., 1985 ). Interleukin-6 acts on mature megakaryocytes by its effects on megakaryocyte ploidy and size ,leukaemia inhibitory factor increases megakaryocyte frequency and circulating platelet levels and interleukin-1 1 increases platelet levels , megakaryocyte ploidy and number of megakaryocyte progenitor cells ( Neben, et al., 1993 ). Thrombocytopenia is defined as any of the bleeding disorders that results from a lack of functional platelets