CELLULARITY AND CELL PROLIFERATION RATES IN HUMAN BONE MARROW

Abstract. Whole body erythroblast numbers and erythrocyte production have been estimated in 14 patients with hypoproliferative or aregenerative anaemia, 9 with hypocellular or fibrotic bone marrow sections or pure red cell aplasia and 5 with hypercellular bone marrow sections. Numbers and production were calculated on the basis of average bone marrow cell and erythrocyte incorporation of 59Fe. Erythroblast generation times were calculated, based on numbers, production and marrow differential counts. H3TDR labelling of erythroblasts was simultaneously studied in vitro. Patients with hypocellular marrows had a significantly decreased whole body erythroblast number, short generation times and normal labelling indices. It is speculated that the low erythroblast number despite normal or rapid multiplication may be explained by stem cell failure. Patients with hypercellular marrows had almost normal erythroblast numbers, significantly prolonged generation times and significantly decreased labelling indices. It is speculated that accumulation of slowly multiplicating erythroblasts in this form of the disease may be related to its previously demonstrated preleukaemic nature.