[The megakaryocyte-thrombocyte system].

The megakaryocytic apparatus of bone marrow and platelets are discussed as a common system whose physiological purpose is to ensure hemostasis when the integrity of the vascular wall is impaired. The principle of operation of the megakaryocyte-platelet system is synthesis, accumulation, and organization of a potent hemostatic potential, its distribution and dispersal along the vascular bed, if inactive, and its new formation at the moment of and at the site of required hemostasis. At the same time in its early and late major functional performance, the elements of the system are stable-at the early stages of megakaryocytopoiesis to the extent to the appearance of a promegakaryocyte and at the stage of platelet hemostatic cork. At the intermediate stages-that of the mature megakaryocyte divided by demarcation membranes and that of reversible aggregation of platelets which have not lost their individuality, the elements of the system are in an unstable state that is ready for disintegration or in a state that does not exclude its possibilities. In the central phase of its existence, the system is in a disintegrated state and appears as proplatelets and platelets. The mechanism of the dispersal and combination of elements and hemostatic potential of the megakaryocyte platelet system serves the apparatus of structural and contractile proteins, which acts as its system-forming factor.