Quantitative Studies of Bone‐Marrow Cells in the Early Stages of Final Haemopoietic Recovery in Irradiated Guinea‐pigs

Abstract

NORMAL active bone marrow is a complex structure in which it is difficult to study microscopically the early precursors of granulocytes and erythroid cells. By using a suitable dose of whole-body irradiation the cellularity of the marrow can be considerably decreased and simplified since the more mature cells, which form the majority of the marrow cells, are eventually eliminated. During recovery of the bone marrow from irradiation of this degree the stem-cell population can be easily stuhed in the initial stages of the recovery.Identification of the early stem cells in bone marrow has reccntly assumed considerable significance since bone-marrow transplantation experiments in animals now have important potential applications in the human being. Bone-marrow replacement in man may evcntually be refined by the use of small concentrated injections of early precursor cells isolated by differential centrifugation of suspensions of foetal or adult hacmopoictic tissues. The purpose of this papcr is to indicate the cells whch are most conspicuous in the early stages of the final recovery of haemopoiesis in the bone marrow of young guinea-pigs recovering from a single dose of whole-body gamma irradiation. The findings are based upon quantitative studies of bone-marrow cells at frequent intervals after irradiation until haemopoiesis appeared to be completely restored. The dose of radiation used in the present experiments produced a marked reduction in cell numbers and also a decrease in the varicty of cells present in the marrow. Thus, on the 14th day aftcr irradiation the marrow had a striking appearance since P. F. Harris FIG. I . Section of i,'iiinra-pii,' bonr 11i.irrow showing small r 1~1 1 1 c i cell\ (ly~nphocytcs) with nucleoli. Eosin W, oratii,'c G and toluidiii blur. ( . (60 ) FIC. 2. Trnrisitional cclls and ,mall lytiiphocytcs in siiicar prcp.irationr of guinea-pig bone iii:irro\v I .+ d.iy\ .iftcr wholrbody irradi.ition. M.icNc.il's tetmchromc. (x 1250.) a, b. c, d. c, f, g R01111d cclls of tranritional type. Note a~i i o~~i i t of cytoplasm, the nuclcnr liofand .irc.i ofp.iIlor it1 the Iicif. l'hc r n i d l roiiiid cells in c, c and f a r e small lymphocytcs.

Recovery of Haemopoiesis after Cyclophosphamide

“…The latter observation confirmed the findings of H a rris [3,5] in guinea pigs. The rise in marrow lymphocytes has been shown to depend on the dose of irradiation [12].…”

Quantitative Study of the Hemopoietic Recovery after a Sublethal X-Irradiation in the Mouse

“…What is the significance of this rapidly changing X-cells population? It is likely that these cells are the same as the lymphoid cells called 'transitional cells' by other authors which assume a relation between the transitional cells and other marrow elements [3,4,5,6,10]. The present results are in contradiction with this assumption.…”

“…Particular attention has been drawn on the accumulation of small mononucleated cells in the bone-marrow of animals recovering from an irradiation [3,4]. These cells, morpho logically similar to the lymphocyte from which they can nevertheless be distinguished by some cytological characters, have received the name o f'transitional cells' [5,6].…”

Observations on the Accumulation of Mononuclear Cells and the Activities of Reticulum Cells in Bone Marrow of Guinea-Pigs Recovering from Whole Body Gamma Irradiation

“…Large numbers of lymphocytes accumulate in the marrow before the substantial recovery of erythropoiesis and granulopoiesis (15). The accumulation is not restricted to guineapigs.…”

“…Previous studies of bone marrow in sub-lethally irradiated guinea-pigs (15) have shown that there is a characteristic phase before the final recovery of granulopoiesis and erythropoiesis. At this time large numbers of mononuclear cells of various sizes are present, and many of them resemble small lymphocytes.…”