Abstract
Morphological, cytochemical, and ultrastructural electron microscopic (EM) studies were performed on blood and bone-marrow cells of case of Ph1-positive chronic ganulocytic leukaemia in megakaryocytic acute transformation. The entire leukaemic cell population was found to consist and of megakaryoblasts and megakaryocytes. Intermediate stages of maturation between blasts and micromegakaryocytes were observed at EM level.