The aim of present study was to optimize culture conditions for pig embryos. Initially, we evaluated three different basic culture conditions. When embryos from electro-activation (parthenotes) or in vitro fertilization (IVF-embryos) were cultured in PZM supplemented with 3 mg/ml bovine serum albumin (PZM-3) in 4-well dishes, in medium covered with oil in 4-well dishes or in droplets under oil, 0%, 33% and 20% of the parthenotes, and 11%, 23% and 20% of the IVF-embryos developed to blastocysts. Subsequently, we examined the development of embryos when they were cultured in 4-well dishes in medium covered with oil continuously for 7 days or cultured under the same conditions but with a change to fresh medium on Days 2 and 4. In this experiment, 23% (no medium change) and 34% (change) of the parthenotes developed to blastocysts, respectively. When IVF-embryos were cultured under similar conditions, 33% and 38% of the embryos developed to blastocysts. Further improvement was achieved when PZM was supplemented with FBS from Day 4. In this experiment, 47% of the parthenotes developed to blastocysts with an average cell number of 57 +/- 7.7. In IVF-embryo group, 49% of the embryos developed to blastocysts with a mean cell number of 60 +/- 6.1. These results indicate that a change to fresh medium and inclusion of FBS in the medium during the late stages of culture can generate a higher proportion of high-quality blastocysts.

Center for Cell Therapy and Tissue Repair VUZV Laboratory Prague Czech Republic