Type V and VI collagen for cohesion of dermal fibrillar structures.

ABSTRACT

Type V and VI collagen were capable to joint each other and with type I and IV collagen, as well as mucopolysaccharides. This capability suggested that these collagens function for cohesion of fibrillar tissue components of dermis. This study demonstrated the locality of these types of collagen in dermis. Fresh specimens of normal skin were fixed in 2% paraformaldehyde in phosphate-buffered saline, overnight. Besides, in order to loosen the twist of collagen fibril, some pieces of the skin specimens were treated by citrate buffer pH 3.0, prior to fixation. The specimens were embedded in Technovit 4100 and the ultrathin sections were stained by antibody to type V collagen and followed by antibody to type I, III, IV and VI collagen. The immune reactant was visualized by gold particles for electron microscopic observation. Type V and VI collagen formed networks in dermis and jointed to collagen fibrils, elastic fibre and basal lamina. Type V collagen was found inside collagen fibrils, broad elastic fibres and junctions. Dermo-epidermal junction showed type V collagen on the dermal aspects of basal lamina and at the sites where anchoring filaments joint to basal lamina, while in junction of mesenchymal tissues, no precise structural components for type V collagen were identified. Type VI collagen wove with type V collagen in dermis and associated with mucopolysaccharides. In conclusion, type V collagen formed networks in dermal interfibrillar space and participated in assembling collagen fibrils and forming broad elastic fibres. Epithelial and mesenchymal cells cohered to the underlying dermal matrix in the junction by type V collagen. Type VI collagen interwove with type V collagen in the interfibrous space and associated with mucopolysaccharides. Types V and VI collagen preserved architecture of dermal matrix.