Immunocytochemical localization of extracellular matrix components in beagle periodontium: I. Collagen types I and III in healthy gingival connective tissue

The localization and identification of types I and III collagen in healthy gingival connective tissue of the beagle dog were investigated using indirect immunofluore‐scent and immunoferritin electron microscopic techniques with affinity purified antibody or IgG. Type I collagen was evenly distributed throughout the lamina propria and the underlying connective tissue in the form of thick collagen fibers. In the lamina propria, these fibers appeared to run from the underlying connective tissue in a perpendicular orientation to the overlying gingival epithelium. Localization of type III collagen was restricted to the lamina propria and the connective tissue around blood vessels. Immunoferritin electron microscopy clearly revealed that type I collagen fibrils have a diameter ranging from 40 to 100 nm and a clear 640 Å cross‐banding pattern. Thin and short collagen fibrils, 18 to 32 nm in diameter, were labelled with antitype III collagen IgG. A 640 Å cross‐banding pattern was rarely observed in these fibrils. Type III collagen fibrils coexisted with type I collagen fibrils in a mixed pattern within the lamina propria and the perivascular space.