Nuclear and cytoplasmic maturation of pig oocytes cultured in the amniotic fluid of developing chick embryos.

Studies were conducted to determine if the amniotic fluid of a developing chick embryo (CEAm) could be used as a co-culture system for the maturation of pig oocytes. In Exp. 1, the pig oocytes were cultured in mTCM-199 (control) or day 3, 4 and 5 CEAm. The maturation rate of pig oocytes in the control vs CEAm was significantly higher (P < 0.001). The maturation rate of pig oocytes cultured in day 3 vs day 4 and 5 CEAm was significantly higher (P < 0.001). In Exp. 2, the pig oocytes were cultured in day 3 CEAm maintained either in a conventional incubator with 40-70% relative humidity or incubator with 5% CO2 in air atmosphere at 37 degrees C or 39 degrees C. A significantly lower maturation rate (P < 0.001) was obtained when CEAm were maintained in an incubator with 5% CO2 gas atmosphere regardless of the temperature. In Exp. 3, pig oocytes cultured in day 3 CEAm and mTCM-199 (control) were fertilized in vitro (IVF). The penetration and male pronucleus (MPN) formation of pig oocytes cultured in day 3 CEAm was significantly lower (P < 0.01) than those cultured in mTCM-199 medium. The results presented here demonstrate that CEAm could be used to induce maturation of pigs oocytes, however its efficacy is influenced by factors such as developmental stages of chick embryos, temperature and gas atmosphere.