The relationship between megakaryocyte ploidy and platelet volume.

The origins and biologic significance of platelet heterogeneity in general, and platelet volume heterogeneity in particular, have been controversial scientific issues during the past decade. Although it has generally been held that specific megakaryocyte properties, especially ploidy level, are important determinants of platelet volume, the precise relationship between megakaryocyte properties and platelet properties is not well defined. The physiologic processes that specifically determine the relationship between megakaryocyte ploidy and platelet volume are unclear, and understanding of these processes has been further complicated due to the multiplicity of experimental and clinical models used to study the problem. Although it is generally true that increases in megakaryocyte ploidy are associated with increases in megakaryocyte volume, it is not well established that platelet volume is also increased during normal or abnormal thrombopoiesis as a direct result of a change in the ploidy level. Reexamination of earlier studies and some recent investigations suggest that changes in platelet volume and megakaryocyte ploidy are in fact dissociated in response to experimental thrombocytopenia. Critical review of the literature concerning the relationship between megakaryocyte ploidy and platelet volume reveals a limited number of conclusions that are well substantiated and emphasizes the relative lack of understanding about the events governing the complex process of platelet production and platelet heterogeneity.