In vitro maturation induces glycoconjugate changes in equine cumuls-oocyte complexes

In vitro matured oocytes (IVM) suffer some inadequacies when compared with in vivo matured ones1. Inadequate IVM can yield under- or overmature oocytes, which will not undergo normal fertilization and embryo development2. Glycoconjugates play a key role in oocyte maturation, and in oocyte-sperm interactions leading to fertilization 3,4, thus the knowledge of oligosaccharide pattern of equine COCs could provide useful information about the comparison between immature and matured COCs. Cumulus enclosed oocytes from abbattoir ovaries were fixed in Bouin’s solution and embedded in paraffin wax either before or after IVM. Sections were stained with 13 lectin (MAL II, SNA, PNA, DBA, RCA120, SBA, HPA, Con A, WGA, GSA I-B4, GSA II, UEA I, LTA). The radiata zone of immature COCs reacted with all used lectins, whereas matured COCs stained with MAL II, SNA, HPA, SBA, and Con A. The zona pellucida of both COCs types bound MAL II, SNA, SBA, and Con A, whereas immature COCs reacted also with RCA120, WGA, and matured ones stained with UEA I. The ooplasm of both types of COCs reacted with HPA, Con A, GSA II, UEA I and LTA, whereas immature oocytes bound also SNA, SBA, WGA, GSA I-B4. These results indicate that IVM modifies glycoprotein pattern of equine COCs and prompted us to undergo further studies to investigate the role of the modified oligosaccharides in oocyte viability, capacity to undergo fertilization and normal embryonic development. References 1. Deleuze S et al Theriogenology. 2009, 72:203-9. 2. Hinrichs K & Di Giorgio LM J Reprod Fertil Suppl 1991, 44:369–74. 3. Dell A et al Biochim Biophys Acta 1999, 1473:196-205. 4. Clark GF & Dell A. J Biol Chem 2006, 281:13853-6.