Pintado, Tomás Ramón

Abstract A light and electron microscopic study was made of the circulating platelets from five patients with variants of the chronic myeloproliferative diseases (agnogenic myeloid metaplasia, chronic granulocytic leukemia, and "megakaryocytic leukemia"). Morphologic abnormalities were found in at least some of the platelets in all of the patients. Presence of giant forms, paucity or absence of granulation, disorganization and scarcity of the microtubules, and haphazard distribution and hypertrophy of the dense tubular and open canalicular systems constituted the main abnormalities. Additionally, there were features of platelet immaturity, including abundant rough endoplasmic reticulum and ribosomes and presence of Golgi profiles, centrioles, and nuclear remnants. The relationship, if any, of these morphologic abnormalities to the hemostatic defects in myeloproliferative diseases remains to be elucidated.