[Importance of cell contacts for the differentiation of the precursor cells of hematopoietic stroma in long-term bone marrow cultures].

The composite adherent cell layer is produced in the culture of bone marrow fragments. On the contrary, in the culture of single cell suspension of bone marrow, only of monolayer of fibroblast-like cells and macrophages is created. After implantation of the adherent cell layer from the Dexter type culture but not from "fibroblast" culture beneath the renal capsule of syngeneic recipients the ectopic hemopoietic sites are formed. Regeneration of the adherent cell layer may occur only in the course of multilayer formation, i.e. one week after bone marrow transplantation but not three weeks after the formation of the adherent cell layer.