A Possible Explanation of the Formation of Long Platelets from Pulmonary Megakaryocytes

Abstract

THE purpose of this communication is to suggest a possible explanation of the formation of the elongated sausage-shaped, sometimes bizarre long platelets that are occasionally encountered in human blood smears. Since Bizzozero¹ first described the platelets as a distinct entity in 1882, much has been conjectured as to the source and mechanism of their formation. Before Wright² described the formation of blood platelets from bone marrow megakaryocytes in the marrow sinusoids in 1910, the thrombocytes were assumed to be formed from disintegration of erythrocytes and leucocytes. Howell and Donahue³ unsuccessfully attempted to show by lung per fusion studies in 1937 that the thrombocytes were formed from megakaryocytes. The latter they believed originated in the lungs. More recently, Humphrey⁴ has added chemical evidence to the hitherto purely morphological evidence that the platelets are derived from the megakaryocytes. But according to Wintrobe⁵: “The mechanism of production of platelets from the cytoplasm of megakaryocytes is by no means clear.”