Transient dyserythropoiesis in repopulated human bone marrow following transplantation: an ultrastructural study

S ummary . Transmission electron microscopy was used to examine marrow samples from 15 patients with aplastic anaemia or acute leukaemia who had been treated with bone marrow transplantation. There were 11 allogeneic, three syngeneic and one autologous graft. The purpose was to estimate the frequency, type and extent of dyserythropoietic change. Transient dyserythropoietic features were substantiated in all cases. Nuclear changes were present in 12 cases, iron laden mitochondria (sideroachrestic phenomena) in 10 and cytoplasmic contacts and/or connections between red cell precursors in 10. Dyserythropoiesis was most conspicuous in the majority of cases between 14 and 28 d after transplantation but it may persist for over 100 d. No deficit in red cell production was noted and it is proposed that dyserythropoiesis in this circumstance is a physiological rather than a pathological phenomenon.