Immunolocalization of proteoglycans in Meckel's cartilage of the rat

The aim of this study was to investigate the presence and distribution of proteoglycans within Meckel's cartilage of rat embryos. A standard indirect immunoperoxidase technique was used on paraffin sections of rat heads. Sections were incubated with monoclonal antibodies recognising core protein epitopes in the proteoglycans versican and CD44. Polyclonal antibodies localized the proteoglycans decorin, biglycan and lumican. Versican was expressed by chondrocytes, but very weekly by the extracellular matrix. Decorin was strongly expressed by both of chondrocytes and the ECM. Both of biglycan and lumican were moderately expressed by chondrocytes, but weakly by the extracellular matrix. CD44 was weakly expressed by chondrocytes only, without staining of the ECM. It is concluded that Meckel's cartilage chondrocytes express the proteoglycans versican, decorin, biglycan, lumican and CD44 at variable levels during development in the rat. Such data are important for a greater understanding of the changes that take place during mandibular development. Further studies are needed to elucidate the exact role of proteoglycans during Meckel's cartilage and mandibular organogenesis.