Figure 1. Periodontal cell segregation. Periodontal ligament (green) and gingival fibroblasts (red) were co-cultured and displayed little segregation after 24 hrs (A). In contrast, pre-osteoblasts (green) and gingival fibroblasts (red) displayed greater segregation when co-cultured for 24 hrs (B). The percentages of cell contacts made by cells with either similar or dissimilar cell types (for periodontal ligament and gingival fibroblasts and pre-osteoblasts) were quantified and compared for cells co-cultured for 2, 24, or 72 hrs (C). Data points represent the mean and standard deviation of 3 independent experiments, each consisting of 10 non-overlapping microscopic fields containing at least 50 cells each.