[Morphological study of responses to mechanical stretching in fibroblasts derived from human periodontal ligaments]

Clonal cell lines established from human periodontal ligaments were used in vitro experiments to ascertain periodontal ligament responses, on the cellular level, to mechanical stretching. A procedure developed by Hasegawa et al. (1985) was used in applying mechanical stretching. Unstretched cultures were used as controls. All cultures were processed for investigations of fine structures, histochemical and cytochemical detection of ALPase activity, and localization of alpha-tubulin. Cultured cells to which mechanical stretching was intermittently applied showed little change in overall appearance, cell shape and arrangement, and distribution of alpha-tubulin. Although fine structural characteristics remained unchanged in both stretched and unstretched cultures, mechanical stretching force clearly increased the intensity of ALPase activity. Histochemical and cytochemical examinations indicated that the added intensity resulted from increases in numbers of cells demonstrating enzymatic activity.