Recovery of Haemopoiesis after Cyclophosphamide

Eosinophil Leucocytes and Recovery from Severe Hypoxia

“…Such a pattern of recovery might be expected if it were the result of increased or restored prolifera tive activity, a few days being needed for the promyelocytes to develop into mature or almost mature forms. A similar pattern of recovery has been observed in the marrow granulocytes following cyclophosphamide administration [18]. The findings would therefore support the hypoth esis [8] that during the severe hypoxia, eosinophil cell-production in the bone marrow had been markedly depressed.…”

Cell-Degeneration Pattern in Bone Marrow and Blood of Guinea Pigs Following Administration of Cyclophosphamide

“…In this connection it may also be relevant that by 24 h there was a significant reduction both in the counts of the mononuclear cells (lymphocytes, monocytes and blast cells) of the blood as well as in the weight of the spleen, whereas no significant change in blood neutrophil numbers was detected until 72 h. To what extent an early reduction in the size of a particular cell-population reflected an actual destruction of cells is uncertain, although the prominence in the 24 h sections of macrophages containing degenerating cells would support such a concept. The suggestion that the myeloid series may have been less affected by cyclophosphamide in this respect, might also be correlated with the observation that during recovery from this drug [8], total myeloid numbers regained (and in fact overshot) con trol levels approximately a week before the erythroid and lymphocyte numbers did. However, attention must also be given to the rather complex changes in the myeloid sub-groups.…”

“…It may be seen from table I that over half the normal myeloid cell-population consists of band and segmented neutrophils, and that at 24 h after cyclophos phamide the number of these later forms was virtually unaffected. In contrast, the early actively-dividing forms (myeloblasts, promyelocytes and myelocytes) showed a dramatic reduction in numbers at 24 h. By 72 h, the counts of the later forms of marrow neutrophil, as well as the counts of neutrophils in the blood, showed a highly significant decrease; by 144 h [8] they had reached levels of less than 5% of the corresponding controls. These observations appear to be consistent with those of H ost [4] who found that in the rat, the non-dividing myeloid cells reached minimum values two days later than the dividing myeloid cells, and with those of H arris [3] who reported that in gui nea pigs following exposure to irradiation, the decline in the number of granulocytes in the early stages varied inversely with their degree of differentiation.…”

“…The techniques used for quantitative study of blood and bone marrow were, except as mentioned below, identical with those used in the earlier study [8]. The animals were killed by exsanguination from the common carotid artery under ether anaesthesia.…”

“…In a quantitative study of haemopoietic recovery over a period of 6-21 days following the injection of a sublethal dose of cyclophos phamide in the guinea pig [8], striking differences were found in the recovery pattern of different cell-lines in the bone marrow. These differences could be attributed to a complex interplay of factors, and in relation to this it seemed important to have more complete informa tion about the pattern of degeneration following the use of this chemo therapeutic agent.…”