title: Mechanical stretching increases the number of epithelial cells synthesizing DNA in culture.
abstract: The influence of mechanical stretching on epithelial (E) cells was examined by culturing E cells derived from the epithelial cell rests of Malassez on a flexible plastic substrate and stretching the substrate by means of an orthodontic screw. A significant increase in the number of E cells synthesizing DNA was observed after just 30 min of stretching. In 17 experiments the ratio of cells labelled with tritiated thymidine in cultures stretched for 2 h to the number of labelled cells in unstretched controls was 1.92 +/- 0.34. An increase in labelling as a result of stretching was found for E cells cultured at either high or low cell-population densities but the effect was most pronounced for E cells cultured at higher concentrations of foetal bovine serum. Morphometric analysis of electron micrographs of stretched and unstretched cultures indicated that the stretched cultures had a higher volume fraction of filamentous structures and more desmosomes per unit length of cell membrane than unstretched cultures. The behaviour of E cells in response to stretching in vitro appears to be similar to the response of the epithelial rests in vivo when the latter are exposed to tension as a result of forces produced by orthodontic techniques.
mesh_terms: D000818:Animals; D001345:Autoradiography; D002452:Cell Count; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron; D013314:Stress, Mechanical; D013552:Swine
chemical_list: D004247:DNA