Dysplastic Platelets and Circulating Megakaryocytes in Chronic Myeloproliferative Diseases. II. Ultrastructure of Circulating Megakaryocytes

Small circulating megakaryocytes were identified in four patients with chronic myeloproliferative disorders, and their morphologic features by light and electron microscopy are described. The morphologic and cytogenetic studies suggest that at least some of these cells are truly mononuclear. The circulating megakaryocytes were associated with the presence of dysplastic platelets. Both findings are thought to represent involvement of the megakaryocytic-platelet line, probably as an expression of stem cell disease.