Recovery of Erythropoiesis after Irradiation: A Quantitative Study in the Rat

Abstract

As in the previous investigation a dose as low as IOO R. caused a marked reduction in the four types of red-cell precursors. Similarly the fall in numbers occurred very soon after irradiation, reductions being seen at the earliest time interval at which observations were made in the present experiments, i.e. at 4 hours after 400 R. At each dose level the more mature non-dividing cells (late and intermediate normoblasts) were again found to be proportionally 365 * Postal address: M.R.C. Radiobiological Research Unit, Harwell, Didcot, Berks. 366 E. V. Hulse Recovery ofErythropoiesis after Irradiation 367 400 R. a series of values in the region of normal or slightly above were followed at 42-56 days by three successive values of about two-thirds of normal. The 70 day value was in the control range. S~H , B. and HERDAN, G. (1954). 'A quantitative study ofthe effects of compound E, compound F and compound A, upon the bone marrow of the guinea-pig.'J. Amit. (Lond.), 88, 115.

Recovery of Haemopoiesis after Cyclophosphamide

“…The absence of overshooting would be con sistent with the findings of Host [7] following cyclophosphamide treatment in the rat. Abnormally high erythroid counts have however been observed during the recovery from irradiation [3,11]. Lymphocytes There was a difference between the patterns of recovery of the small lymphocytes on the one hand and the transitional cells and medium lymphocytes on the other.…”

“…The present results indicate that the patterns of regeneration are different for each of these cell-lines; they will therefore be considered separately. It is perhaps necessary to add that recovery has only been studied over a period of 21 days and that long term effects such as occur after irradiation [11,12] have not been excluded. Furthermore, the changes in the spleen weight (table IV), and particularly the striking increase in weight at 12 days after cyclo phosphamide, serve to emphasize that the patterns of recovery seen in the bone marrow need to be considered in relation to changes in the rest of the lympho-myeloid complex.…”

A Study of the Interdependence of Red Cell and Bone Marrow Stem Cell Populations

“…Consequently the peaks of the haemoglobin concentration in our findings are a direct result of the peaks in reticulocyte numbers. The investigations reported by Hulse (1963)~ on the levels reached by normoblast and reticulocyte numbers at various times after whole body irradiation, show that a reticulocyte peak appears when a peak in normoblast numbers has passed through the normoblast stages and enters the circulation. The reticulocyte peaks in our case, therefore, result presumably from an increase in the rate of initiation of differentiation, caused by an incrcase in the concentration of erythropoietin in response to a fall in the haemoglobin level.…”

Quantitative Cell Counts of the Bone Marrow and Blood and their Secular Variations in the Normal Adult Rat

“…During a quanti tative study of the changes in haemopoiesis after irradiation (17,18,19,20,21,22) a total of 81 noi'mal unirradiated rats were ex amined by a method based on that of Yoffey (36). As comparatively little has been published on values obtained using quantitative methods and as the present series is much larger than those pre viously published, an analysis of the data from the normal rats has been made.…”