IN-VITRO DEVELOPMENT OF IN VITRO-MATURED PORCINE OOCYTES FOLLOWING CHEMICAL ACTIVATION OR IN-VITRO FERTILIZATION

Porcine cumulus-oocyte complexes were cultured in BSA-free Whitten's m edium or modified Medium 199, each supplemented with porcine follicula r fluid (PFF) and hormonal supplements (OMWM and OMM199, respectively) for 20 h; they then were cultured without hormonal supplements for an additional 20 (experiments 1 and 3) or 24 h (experiment 2). At the en d of culture (experiment 1), the intracellular glutathione concentrati on was higher (p < 0.05) in oocytes matured in OMWM vs. OMM199. After activation by Ca2+ ionophore (experiment 2), the incidence of activati on in the OMWM group was lower (p < 0.01) than in the OMM199 group. Ho wever, the incidence of pronuclear formation was higher (P < 0.01) in the OMWM group than in the OMM199 group at 8 h after activation. The p ercentage of embryos that developed to the morula stage was higher (p < 0.01) in the group matured in OMWM vs. OMM199 after 5 days of cultur e. After in vitro fertilization (experiment 3), the incidence of male pronuclear formation and the percentage of monospermic oocytes that fo rmed one male and one female pronuclei were higher (p < 0.05) after ma turation in OMWM vs. OMM199. The percentage of cleaved embryos that de veloped to the 8-cell and morula stages was higher (P < 0.05) in the O MWM group as compared to the OMM199 group. These results indicate that culture in modified Whitten's medium as compared with a standard medi um (modified Medium 199) improves cytoplasmic maturation of porcine oo cytes) as evaluated by intracellular glutathione content, pronuclear f ormation, and development in vitro after artificial activation or fert ilization in vitro.