Composition of human periodontal ligament cells in tissue culture

The cells in the PDL of monkeys have been demonstrated to have an unusual growth behavior in vitro since fibroblast-like cells have been reported to grow on top of epithelial-like cells. In this study growth of epithelial-like cells along with fibroblast-like cells was seen in human PDL from three out of 15 permanent teeth when explantation technique was used whereas only fibroblast-like cells were seen after enzymatical degradation. Occasionally fibroblast-like cells were seen growing on top of epithelial-like cells.