The Use of the Supravital Method in a Study of Cells Susceptible to Damage in Smears of Normal and Regenerating Bone Marrow

Cells susceptible to damage during smearing were identified in the different cellular compartments of normal and regenerating bone marrow of the guinea pig by comparing differential counts on fixed dry smears and on supravitally stained wet preparations. The comparisons are considered valid since 1) the number of damaged cells was negligibly low in supravital preparations; 2) it could be shown that cell classification and 3) cell distribution corresponded on the two types of preparations. In smears of normal marrow the majority of damaged cells were myeloid cells, although the most fragile cell appeared to be the monocyte. In normal marrow, erythroblasts and lymphoid cells did not damage in significant numbers. During recovery from sublethal irradiation the number of damaged cells increased significantly in each cell compartment at the time when that compartment commenced its regeneration.

In contrast to normal marrow, at the time of lymphoid regeneration 60 per cent of transitional cells had damaged and at the start of erythroid and myeloid regeneration 40-50 per cent of erythroid and myeloid cells were concealed on smears by damage. Labeling with ³H-thymidine indicated that in smears of normal as well as of regenerating marrow, a large proportion of cells susceptible to damage in the various cell compartments was capable of proliferation.