Bone marrow sinus and cell egress in human leukaemia: a morphometric study of core biopsies using wide-field electron microscopy.

Bone marrow biopsy specimens obtained from 24 untreated patients with several types of acute leukaemia (AL) and eight patients with chronic myelocytic leukaemia (CML) were prepared without decalcification for electron microscopy. A new type of transmission electron microscope (LEM 2000) was used for wide-field observation, and the venous sinuses were morphometrically evaluated on micrographs using an automatic image analyser. No differences were found between either AL or CML bone marrows and the controls in the diameter, circumference, or luminal and endothelial area of sinuses. No degenerative changes were observed in the sinus endothelium of either the AL or CML patients, but the adventitial cell cover in sinuses was significantly less in both AL (P less than 0.001) and CML (P less than 0.001) patients than in the controls, indicating a close relationship between the decrease in adventitial cell cover and increase in migrating leukaemia cells. In addition, the sinus endothelium in CML had significantly (P less than 0.03) more pores than in AL patients and three or more leukaemic cells in migration through the same large pore were occasionally found in the CML patients. These findings suggest that leukaemic cell migration in AL differs from that in CML.