Intercellular contacts between fibroblasts in the periodontal connective tissues of the rat

The type and number of cell contacts between fibroblasts were studied in three structurally distinct varieties of periodontal connective tissue in the rat mandible (periodontal ligament of the incisor, enamel-related connective tissue of the incisor and periodontal ligament of the molar). Three types of cell contact were observed in all tissues, namely simplified desmosomes, gap junctions and close contacts. When considered in terms of number per 50 micrometer (2), percentage of the membrane profile occupied and mean length, simplified desmosomes in the enamel-related connective tissue of the incisor were significantly higher than in the periodontal ligaments. For gap junctions, the only significant difference found was in the number per 50 micrometer (2) between the two periodontal ligaments. For close contacts the number per 50 micrometer (2) was significantly higher for the periodontal ligament of the incisor than for the other two tissues. However, when considered as a percentage of the membrane profile occupied, the only significant difference remaining was with the enamel-related connective tissue.