A freeze‐fracture study of the periodontal ligament of the rat

Fibroblasts of the rat periodontal ligament were studied in situ by the freeze‐fracture technique. Large surfaces of the protoplasmic and extracellular faces of the cell membrane as well as, the membranes of the RER, Golgi apparatus, and other cytoplasmic organelles were viewed at the ultrastructural level. Intramembrane particles representing membrane proteins were visualized, and their concentration in various membranes measured. Features of the fibroblast cell surface appearing as rough patches were interpreted to represent areas of possible cell‐to‐matrix interaction. The use of the freeze‐fracture technique in further studies of PDL fibroblast‐matrix contact is discussed.