Lectin‐induced blockage of developmental processes in preimplantation mouse embryos in vitro

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Abstract
This study attempts to assess the developmental importance of cell surface glycoconjugates of preimplantation mouse embryos. This was done by incubating early embryos in various lectins and analyzing subsequent development. If specific cell surface glycoconjugates (lectin receptors) are linked to specific developmental processes, such as cell division, compaction, and blastocyst formation, then different lectins should block these different developmental processes. The results show that wheat‐germ agglutinin (WGA; N‐acetyl‐D‐glucosamine‐specific) at 50 μg/ml prevents the cell division of four‐cell embryos. However, this effect of WGA occurs only in embryos with intact zonae pellucidae. Concanavalin A (Con A; α‐D‐glucose and α‐D‐mannose‐specific) treatment, 20 μg/ml, of four‐cell or early eight‐cell embryos prevents compaction, the first major change in cell shape in early mouse embryogenesis. Divalent succinly Con A does not affect development, suggesting that the Con A effect is due to crosslinking of cell surface glycoconjugates. Exposure of four‐cell or early eight‐cell embryos to 10 μg/ml Lotus Tetragonolobus puprureas agglutinin (LTA; α‐L‐fucose‐specific) or 25 μg/ml Limulus polyphemus agglutinin (LPA; sialic acid‐specific) allows compaction or development to the morula stage, but blocks blastocyst formation. All lectins tested retard cell division to some extent. Late morulae and early blastocysts are more resistant than earlier stages to all of the lectins studied. This study demonstrates that very low concentrations of these lectins affect different developmental processes, presumably based upon their sugar specificities.