| Abstract: | We investigated the ultrastructural changes in the hematopoietic microenvironment of the bone marrow obtained from 15 untreated patients with chronic myelocytic leukemia (CML) in the chronic phase by transmission and scanning electron microscopy using the cryofracture technique. Examination of the unde-calcified bone marrow specimens confirmed extensive hyperplastic granulopoiesis. In the stroma, fat cells were scarce or absent. Macrophages were increased and scattered throughout the marrow. The cytoplasm contained abundant cellular debris and crystals of the Charcot-Ley den type. Slender reticular cells were inconspicuously located between proliferating myeloid cells. A few foci of fibrosis were occasionally observed. The sinus endothelium generally retained its continuity, and no features suggesting complete deterioration of the sinus were evident. However, certain alterations in the sinus wall were noted in the process of leukemia cell migration. Many cells migrated trans-cellularly into the circulation through transient large openings in the sinus endothelium. |
