CFU-F from dog marrow: a colony assay and its significance

A colony assay method is described for studying dog fibroblast colony development in marrow cells derived from resected ribs. The assay showed an increased number of fibroblast colony forming units (CFU-F) in cell suspensions prepared from resected ribs compared to cell suspensions prepared from bone marrow aspirates or from peripheral blood. A linear relationship between the number of cells plated and the number of fibroblastoid colonies was demonstrated in each case. The proportion of phagocytic cells was lower in cultures prepared from resected ribs than in those prepared from bone marrow aspirates. Staining for acid phosphatase and with sudan black showed differences between phagocytic cells and non-phagocytic fibroblasts. When left in plastic dishes for 2 hrs, 81% +/- 10% of the CFU-F adhered to the plastic dishes. Velocity sedimentation separation showed a modal sedimentation rate of 6.49 mm/h.