LECTIN-HISTOCHEMICAL ANALYSIS OF GLYCANS IN OVINE AND BOVINE NEAR-TERM PLACENTAL BINUCLEATE CELLS

Chorionic binucleate cells (BNC) occur in several ruminants including cow, deer, goat and sheep. They migrate through the chorionic tight ju nction to fuse with uterine epithelial cells and discharge their granu les into maternal connective tissue. We have compared the BNC of near- term, resin-embedded, ovine and bovine placentae using 15 biotinylated lectins and an avidin-peroxidase revealing system. There was pronounc ed conservation of saccharides between the two species. Several sub-ty pes of N-glycan were present, with highly branched structures being ab undant, as shown by Galanthus nivalis, Pisum sativum and Phaseolus vul garis (leuko) agglutinins. Among the non-reducing terminal saccharides conserved were GalNAc alpha 1,3(Fuc alpha 1,2)- Gal beta 1,4GlcNAc be ta 1-, GalNAc alpha 1,6Gal beta 1-, Gal beta 1,4GlcNAc- and Gal beta 1 ,3GalNAc alpha 1- shown by Dolichos biflorus, Wister-in floribunda, Er ythrina cristagalli, and Maclura pomifera agglutinins, respectively. A rachis hypogaea and Glycine max agglutinins tended to bind to bovine B NC at different stages of maturity, while fucosyl residues detectable by Tetragonolobus purpureus and Ulex europaeus-1 agglutinins were not observed in either species. The only major difference related to sialy l residues, with alpha 2,3-linked sialic acid being present in bovine (Maackia amurensis, Limax flavus) and alpha 2,6 sialic acid being pres ent in ovine (Sambucus nigra agglutinin) cells. This conservation of g lycan may be related to glycosylation of peptide hormones in the granu les, and may thus be important in the targeting of these hormones to t heir receptors.