Light and electron microscopic demonstration of wheat germ agglutinin binding in the pericellular matrix of rat mandibular condylar cartilage.

Binding of wheat germ agglutinin to rat mandibular condylar cartilage was investigated with the avidin-biotin peroxidase complex. Binding sites were observed in the pericellular matrix of the hypertrophic cell zone. Two distinct patterns were identified: one showed binding to the pericellular matrix without apparent contour; in the other binding was confined to the matrix but with conspicuous condensation forming a pericellular rim. The first binding pattern was seen particularly in the upper part of the hypertrophic cell zone adjoining the mature cell zone; the second was localized in the lower part of this zone adjacent to the site of endochondral calcification. The binding sites in the pericellular matrix are assumed to be NANA and/or GlcNAc in view of the sugar specificity of this lectin. The presence of these binding sites in this region may be due to a structural alteration or modification of proteoglycans in the course of preparation for endochondral calcification.