Evidence for endothelial junctions acting as a fluid flux pathway in tensioned periodontal ligament

A continuous tension load of 1.0 N applied to the rat maxillary first molar for 30 min led to a significant increase (p < 0.05) in the mean number of junctions/microns of endothelial perimeter. The mean number of junctions/microns was compared with the mean number of tissue channels/microns 2 as previously reported by fitting linear and quadratic equations. An increase in the mean number of junctions/microns was associated with an increase in mean number of tissue channels/microns 2 (p < 0.01) in control and experimental periodontal ligament. Significant increases in the mean number of junctions/microns occurred in the middle-third zone for venous capillaries (p < 0.01) and in the tooth-third zone for postcapillary-sized venules (p < 0.001). It is concluded that the endothelial junctions of venous capillaries and postcapillary-sized venules provide significant pathways for fluid transport across the tensioned walls of the microvascular bed of the periodontal ligament.