Immunohistochemical study of collagens of the extracellular matrix in cartilage of Sepia officinalis.

Abstract

We used various anti-collagen antibodies to perform indirect immunofluorescent staining of cartilage sections from cuttlefish (S. officinalis). On ultrathin sections and collagen fibril preparations from the same tissue, we performed immunostaining with colloidal gold. The extracellular matrix (ECM) of S. officinalis cartilage reacted intensely and homogeneously with an antibody directed against type I-like collagen isolated from the cartilage of cuttlefish and with anti-rat type V collagen antibody. A weak reaction was observed with anti-fish and anti-chicken type I collagen antibodies, while no reaction was observed with anti-rat type I and anti calf type II collagen antibodies. Anti-chicken type II, anti calf type IX and type XI collagen antibodies reacted weakly with ECM, while stained cell bodies and cell processes reacted more intensely. A similar pattern of reaction was observed on cartilage section and isolated collagen fibrils prepared for electron microscopy. These findings suggest that ECM of cuttlefish cartilage may be composed of molecules similar to the type I, type V, type IX and type XI collagen molecules of vertebrates. Cephalopods have evolved a cartilage of structure and macromolecular organisation similar to that of vertebrate cartilage. However, the main molecular components of S. officinalis cartilage--type I-like and type V collagens--differ from those of vertebrate cartilage. We suggest that this type I-like collagen can be considered an initial step toward the evolution of type II collagen typical of vertebrates.