[The effect of the humoral action of the cells from chick embryo hematopoietic organs on the colony-forming capacity of normal mouse bone-marrow cells and in activated erythropoiesis].

The cells of chick embryo hematopoietic organs were cultivated together with mouse bone marrow cells in bicameral diffusion chambers under normal conditions and in activated erythropoiesis. The yolk sac cells inhibited colony formation on the 2nd, 4th days of development, the hepatic cells--on the 8th, 12th days, the splenic cells--on the 13th, 17th days, and the bone marrow cells--on the 15th day. The cells of the yolk sac sharply intensify the formation of colonies by the marrow mononuclears, in particular, on the 6th developmental day in activated erythropoiesis. The yolk sac (on the 4th, 6th days of development), the liver, and the spleen produce humoral factors which facilitate the formation of erythroid colonies by the marrow cells of mice. The cells of a 4-day-old yolk sac inhibit the formation of granulocytic colonies, and the synthesis of inhibitors ceases in a 6-day-old yolk sac. It is suggested that the synthesis of local humoral inhibitors of the proliferation of colony-forming units controls the intensity of hematopoiesis in the organ and, by reducing proliferation, facilitates the emergency of cells into differentiation independently, according to the law or under the effect of local humoral poetins.