The immunohistochemical distribution of collagens type IV, V, VI and of laminin in the human oral mucosa.

The distribution of collagens type V (form AB2) and VI was investigated on cryostat sections of normal human oral mucosa by indirect immunofluorescence. For comparison, antibodies to fragments of type IV collagen and laminin were also used to delineate basement membrane containing structures. All antibodies used were raised against human proteins. Type V collagen appeared as a microfibrillar structure throughout the interstitium, apparently touching but not being present within epithelial or vascular basement membranes. Microfibrils in blood vessel walls were limited to the intimal layer. Pericellular areas were not specifically stained. Type VI collagen appeared as an almost amorphous stromal structure becoming more prominent and more fibrillar in the upper connective tissue papillae. Intense staining was observed in the media of blood vessels and around smooth muscle cells. A possible role of type VI collagen in tissue stabilization may be expected from this ubiquitous and abundant distribution. The findings identify types V and VI collagen as important structures in the oral mucosa and serve as a basis for understanding morbid changes.