he architecture of the gingival and interdental ligaments was studied in celloidin-embedded sections of tissue from young adult marmosets. The animals were free of clinical or histologic manifestations of inflammatory gingival disease. The fibre groups classically described were observed. In addition, several groups of fibres which do not fit into the previous classification were present. The semicircular fibres arise from the cementum near the cementum enamel junction, traverse the free marginal, facial and lingual gingiva, and insert into a comparable position on the opposite side of the tooth at a level just apical to the circular fibres. The transgingival fibres arise from the cementum of one tooth and traverse the free marginal gingiva of an adjacent tooth, and the intergingival fibres course in the free marginal gingiva on both the facial and lingual surfaces of the teeth. Since these fibre groups make up the bulk of the connective tissue framework of the marginal gingival tissues, and they arise from the root surfaces or gingiva of adjacent teeth, there is a major interdependence among the various segments of the gingiva.
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