EFFECT OF CULTURE MEDIUM ON THE DEVELOPMENT OF PIG EMBRYOS OBTAINED BY SOMATIC CELL NUCLEAR TRANSFER.

Culture medium is an important factor in in vitro embryo development. The efficacy of two culture media, the modified New Carolina State University-37 (NCSU-37) and the Porcine Zygote Medium-3 (PZM-3), for the development of pig embryos produced by somatic cell nuclear transfer was compared. A piezo manipulator was used to prepare enucleated oocytes and to perform somatic cell nuclear transfer. Intact reconstructed oocytes were selected and cultured at 38.5°C, 5% CO2,5% O2, 90% N2 for 7 days and then split into two groups. Group 1 was cultured in a glucose-free NCSU-37 medium supplemented with pyruvate and lactate for the first 2 days then subsequently cultured in a conventional NCSU-37 medium containing glucose for another 5 days. Group 2 was cultured in a PZM-3 medium for 7 days; with 10% fetal calf serum supplemented on day 5 (day 0 being the day of nuclear transfer). Cleavage rates, blastocyst rates and the number of cells in blastocyst on day 7 were compared between the groups. Cleavage and blastocyst rates in PZM-3 medium were significantly higher than those in NCSU-37 (79.2% vs 72.7% and 14.6% vs 10.5%, respectively; p < 0.05). The mean number of cells per blastocyst in group 1 was significantly higher than that in group 2 (48.4 vs 38.9, p < 0.05). In conclusion, the results suggested that the PZM-3 medium combined with serum is more suitable for the development of pig embryos produced by somatic cell nuclear transfer. [ABSTRACT FROM AUTHOR]