Oviduct-Specific Glycoprotein Modulates Sperm-Zona Binding and Improves Efficiency of Porcine Fertilization In Vitro1

Oviduct-specific glycoprotein (OGP) displays estrus-associ-ated regional and temporal differences in expression and local-izes to the zona pellucida, perivitelline space, and plasma mem-brane of oviductal oocytes and embryos, suggesting that it may have a role in regulation of fertilization and/or early embryonic development. The aims of this study were to evaluate the effect of exogenous OGP on in vitro fertilization (IVF) and embryo development in the pig using a defined serum-free culture sys-tem. In vitro-matured porcine oocytes were incubated with ho-mologous OGP (0, 1, 10, 20, and 40 mg/ml) for 3 h and then washed prior to IVF. Exposure of oocytes to 10 or 20 mg/ml porcine OGP (pOGP) significantly reduced the incidence of polyspermy compared with the control (P, 0.01) while main-taining high penetration rates. When oocytes, spermatozoa, o