CHARACTERIZATION OF GLYCOCONJUGATE EXPRESSION DURING DEVELOPMENT OF MECKELS CARTILAGE IN THE RAT

The staining patterns of 24 biotinylated lectins were analyzed in seri al sections of the mandible of 13- to 21-day-old rat embryos by means of the avidin-biotin-peroxidase method. A ubiquitous distribution of b inding sites was demonstrated after incubation with Con A (Canavnlia e nsiformis), DSL (Datura stramnonium; except bone matrix), and WGA (Tri ticum vulgare). ECL (Erythrina cristagalli), GSL I(Griffonia simplicif olia), SJA (Saphora japonica), VVL (Vicia villosa), DBA (Dolichus bifl orus), UEA I(Ulex europeus), and LTA (Lotus tetragonobolus) were const antly negative. In early stages of development, GSL II (Griffonia simp licifolia II) was a selective marker of prechondral blastema. In contr ast, PNA (Arachis hypogaea) did not stain condensing mesenchyme. Durin g chondrogenesis of Meckels's cartilage a general decrease of lectin b inding was observed. Mature cartilage matrix was constantly negative. Chondrocytes were marked by the lectins PSA (Pisum sativum), WGA, PHA- E, and PHA-L (Phaseolus vulgaris E and L). A strong GSL II binding was restricted to the mesial-superior region of the perichondrium. In lat er stages, several lectins revealed significant differences between pr eskeletal (''central'') areas and the remaining (''peripheral'') mesen chyme. A clear binding reaction was noted in central regions by applyi ng LEA (Lycopersicon esculentum) and STL (Solanum tuberosum), while th e peripheral tissue was only faintly stained. Developing bone was spec ifically marked by succinylated WGA (sWGA). The lectins LCA (Lens culi narus) and RCA (Ricinus communis) bound to fibers and extracellular ma trix of the connective tissue. Jacalin (Artocarpus integrifolia) and S BA(Glycine max) binding sites were found in macrophages. Affinity of V AA (Viscum album) increased parallel with maturation of endothelial ce lls. Specific lectin-binding patterns revealed no correlation with the distribution of glycosaminoglycans. The results demonstrate a general reduction of oligosaccharide structures during development of Meckel' s cartilage. From our observations we conclude that intralaminar gluco se and/or mannose sequences as well as terminal sialic acid molecules are ubiquitously distributed, while terminal a-fucose was constantly n egative. Lectin-binding patterns of macrophages may reflect the presen ce of specifically linked terminal galactose. Our findings indicate th at oligosaccharides terminating in N-acetylglucosamine are bone-specif ic. The significance of the restricted staining of the perichondrium b y GSL II remains to be elucidated.