Identification of human megakaryocytes with rhodanile blue

Using the oxazine dye rhodanile blue, large typical megakaryocytes and small megakaryocytes (micromegakaryocytes) from the bone marrows of normal persons, and from patients with a variety of preleukemic disorders, acute lymphoblastic and nonlymphoblastic leukemia, chronic granulocytic leukemia, and idiopathic thrombocytopenic purpura as an example of nonmalignant but abnormal megakaryocytopoiesis, showed intense pink staining of the cytoplasm. This pink metachromasia was not obliterated by prior digestion with either diastase or ribonuclease, but was markedly diminished or obliterated by preincubation with hyaluronidase, suggesting that the stain may detect a high content of acid mucopolysaccharides in megakaryocytes. Since the stain is simple, direct, and reproducible, it may represent a useful addition to the cytochemistry of megakaryocytes and complement the more complex immunologic techniques available currently.