Ultrastructural studies on the gingival connective tissues of experimental gingivitis

This histological study was undertaken on the gingival connective tissue in experimental gingivitis. Gin-pack (#2) was ligated around 3/|/3 tooth neck from 0 to 9 days in an adult male Macaca irus monkey that was given soft food and water.Gingival biopsy specimens were taken before (3) and after (3) the experimental period. They were studied at light microscopic and ultrastructural levels. The following results were obtained:1) 3 (control gingiva): There was no evidence of inflammatory changes. Typical half desmosomes were viewed between the epithelium and the basal lamina. In the connective tissue, active fibroblasts were found with a high collagen content.2) 3(inflammatory gingiva): The tissue was vascularized and poor in collagen. A variety of inflammatory cells were found. Sometimes many lymphocytes were found in close contact with fibroblasts.3) Fibroblastic phagocytosis of collagen was observed.4) Phagocytosed collagen fibrils in an electron-dense matrix were enclosed by unit membrane. The unit membranes were closely associated with and fused to several lysosomal dense bodies. Also collagen fibrils were seen interiorized in phago-lysosomes and residual bodies.5) Since FLS-like structure was not observed extracellulary, the loss of collagen fibrils may be due to fibroblastic phagocytosis.