The ultrastructural localization of
collagens type V and VI in normal human gingival mucosa was investigated by immunoelectron microscopy. Twenty biopsies were fixed in
dimethylsuberimidate and
shock-frozen in slush
nitrogen.
Collagen type V was mainly located to meshworks of uniform nonstriated microfibrils of 12 to 20 nm width, which preferentially appeared in larger spaces between cross-striated major
collagen fibrils. Occasionally single microfibrils of
collagen type V fanned out from the ends of major
collagen fibrils, which may indicate a role as a core fibril.
Collagen type V was not found in the subepithelial basement membrane and the immediately adjacent stroma.
Collagen type VI was detected in a loose reticular network of unbanded microfilaments that were morphologically distinguishable by knoblike protrusions every 100-110 nm. These microfilaments were found in the vicinity, but not as an intrinsic component, of the subepithelial basement membrane. Single filaments of
collagen type VI filaments appeared to form bridges between neighboring cross-striated major
collagen fibrils, suggesting an interconnecting role for this
collagen type. The method presented appears to be excellently suited to study the normal and pathological supramolecular organization of the oral extracellular matrix.