A lectin binding analysis of glycosylation patterns during development of the equine placenta

The glycosylation of the equine interhaemal barrier and areola was studied throughout the period of gestation. Placentae of 35, 37, 50, 119, 152, 200, 280 and 300 days gestation were investigated, using semithin plastic embed ded sections and a panel of 15 biotinylated lectins with an avidin-peroxida se revealing system. Glycosylation of the trophoblast and maternal epitheli um showed the most change during the first 50 days of gestation, being asso ciated with the initial stages of adhesion and attachment. In the trophobla st, non-bisected tri/tetraantennary complex N-glycan was only evident after day 37 and terminal N-acetyl galactosamine, alpha 2,3- and alpha 2,6-linke d sialic acids disappeared at the same time. The areolar trophoblast exhibi ted some differences from microcotyledonary areas, especially with respect to 2-deoxy, 2-acetamido alpha-galactose and tri/tetraantennary, non-bisecte d complex N-glycan, suggesting that the differences in function between mic rocotyledonary and areolar trophoblast are reflected at both the morphologi cal and the biochemical level. Granules of the maternal uterine epithelium bound many lectins, particularly those with specificity for bisected and no n-bisected bi/triantennary N-linked glycan, a-deoxy, 2-acetamido alpha-gala ctosyl, beta-galactosyl and some fucosylated termini. Binding to sialic aci ds in alpha 2,3 and alpha 2,6-linkage was sparse. Maternal and fetal capill aries showed little change in glycan expression over the period studied, be ing rich in bisected and non-bisected bi/triantennary N-linked glycan and s ialic acids, with some terminal N-acetyl galactosamine and no detectable te rminal fucosyl residues. (C) 1999 W. B. Saunders Company Ltd.