[The humoral nature of the colony-stimulating action of bone marrow cells on stromal colony formation in bone marrow cultures].

In 24 hours adherent marrow cell cultures (AMCC) were represented by single stretched fibroblasts. In non-feeder-supplemented AMCC most of the CFU-f remained single fibroblasts or passed through 1-3 cell doublings [correction of dudlings]. The colony stimulating activity of irradiated marrow cells was found to be diffuse across the Millipore filter, which seems to indicate that haemopoietic marrow cells produce a colony stimulating factor which is required for triggering the CFU-f from the Go-period of the cell cycle into cell proliferation.

[Colony-forming fibroblast precursors of the circulating blood].

Colony-forming fibroblast precursors were detected in circulating blood of adult guinea pigs by CFUf in vitro colony assay. SFU amount to 0.9 +/- 0.

[Bone tissue formation in organ cultures of human bone marrow].

Bone formation in adult human bone marrow organ cultures is described. When culturing marrow fragments, thick bone lamina is formed. It has well-mineralized trabecular bone matrix with bone cells incorporated and is lined with osteoblast-like cells.

[Dynamics of the mineralization of the ground substance in newly formed bony tissue in organ cultures of mouse bone marrow].

Na-beta-glycerophosphate was added to the organ culture medium of mice marrow fragments. New bone ground substance is formed, its mineralization degree and morphology being highly dependent upon glycerophosphate addition and removal periods. Complete or partial ground substance mineralization occurs, in last case calcium insoluble salts may be found in young apical or in old basal parts only.

[Formation of bone tissue by mouse bone marrow cell suspensions in organ culture].

Adult mouse bone marrow cell suspensions prepared by trypsinization were cultivated in gelatin sponges on millipore filters. When HAWP filters were used, multilayer bone structure was formed. It contained mineralized ground substance, incorporated bone cells and osteoblast layer.