Platelets are blood circulating specialized subcellular fragments, which are produced by megakaryocytes. Platelets are essential for hemostasis and wound healing but also play a role in non-hemostatic processes such as the immune response or cancer metastasis. Considering the immediate precursors of platelets, normal megakaryocyte development is essential for normal platelet function. Although much is known about platelet development, some aspects of platelet production remain poorly understood.Megakaryopoiesis is a complex process whereby the multipotent erythroid/megakaryocyte progenitors that commit their fate from hematopoietic stem cells (HSCs) differentiate into megakaryocytes. During maturation, megakaryocytes undergo several dramatic phenotypical changes including polyploidization and the development of a demarcation membrane system. The purpose of this thesis is to further elucidate novel mechanisms and aspects involved in megakaryopoiesis and the effect they have on platelet function, and how to assess with newly developed tests platelet functional characteristics.