[Colony- and cluster-forming ability of mouse bone marrow depending on its functional state and cultivation conditions].

The dependence of colony- and cluster-forming ability (CFA and CLFA) of bone marrow cells on its initial state and the conditions of cultivation was studied. Intact mice and mice with stimulated erythropoiesis were used in the experiment. The bone marrow was separated on a density gradient and cultivated in diffusion chambers (DC) on a plasma clot with addition of the tissue fluid of a chick embryo. Uni- and bicameral milliporous cylindrical microchambers were used. The DC were put into the abdominal cavity of mice first given a cyclophosphamide injection and on the vascular membrane of the chick embryo. The bicameral DC were employed in cocultivation of yolk-sac cells of a 4-week-old chick embryo and bone marrow mononuclears of both experimental groups. The CFA and CLFA of bone marrow mononuclears depend in respect of quantity and quality on the condition of its cultivation rather than on its initial state. It is concluded on the basis of tests for the inductive effects of yolk-sac cells on the CFA and CLFA that in study of cell inductors under conditions of DC and in cultivation in vivo one should take into account the initial state of the hematopoietic target cells, the sensitivity of cells to stimulation, the conditions of cultivation which allow the cells to emerge into the process of this or that differentiation even in the presence of an inductor.