Intercellular junctions in human tooth-pulp cells in culture in vitro revealed by freeze-fracture, lanthanum impregnation and filipin treatment.

Three kinds of intercellular junctions were detected between human dental pulp cells in explant culture with electron microscopy included filipin detection for cholesterol; desmosome-like junctions observed on ultrathin sections probably contribute to the cohesiveness between cells in culture. Gap junctions, responsible for intercellular communication, exhibited two morphologies on freeze-fracture replicas: a conventional arrangement of their intramembranous particles and a crystalline array corresponding to the formation stage of junctions. Primitive tight junctions were detected on freeze-fracture replicas but not on ultrathin sections. It is likely that they contribute to the cell-to-cell adhesion under culture conditions.