Collagen fiber reunion in wound repair: transmission electron microscopic study of rat gingiva

The purpose of this study was to characterize connective tissue at the site of reunion following surgical injury of the transseptal fiber system in rat molars. Eight conventional albino rats aged 50 days were incised interdentally and the lesions allowed to heal for 14 days followed by specimen preparation for transmission electron microscopy. Four specimens with identifiable areas of fiber attachment at the light microscopic level of magnification were selected for a detailed ultrastructural examination. Transitional connective tissue consisted of thin (250-375 A) and thick (greater than or equal to 450 A) collagen fibrils at a ratio of 41/59 mainly arranged as aggregates of uniformly sized fibrils. Fibril thickness in the vicinity of fibroblasts (n = 40) varied at a ratio of 65 (thin)/35 (thick). Distribution and spatial arrangement of fibrillar components indicate that the site of reunion is characterized by separate aggregates of fibrils rather than alignment of individual collagen fibrils of varying thickness suggestive of covalent linkage.