Studies On Factors Affecting The In Vitro Development Of Porcine Embryos

Factors affecting the in vitro development of porcine parthenogenetic embryos were investigated in this study.Significantly more porcine parthenogenetic embryos developed to blastocysts when they were cultured in NCSU-23 medium supplemented with 0.5% BSA for 7 days (36.7%) in comparison with them cultured in NCSU-23 medium supplemented with 5%, 10%, or 15% FCS (11.8%, 18.5% or 10.3%, P<0.01). Addition of 25% or 50% TCM-199 to NCSU-23 medium resulted in a significant decrease in the blastocyst yield (11.1%, 1.1% vs 30.1%, P<0.05), although no significant difference was found in the cleavage rate (83.4%, 82.6% vs 89.6%, P>0.05). Decreasing the concentration of hypotaurine in NCSU-23 medium from 5 mmol/L to 2.5, 1.0 or 0.5 mmol/L did not affect the cleavage rate and blastocyst yield of activated porcine oocytes (P>0.05). However, eliminating hypotaurine from NCSU-23 medium resulted in a dramatically decrease in the blastocyst development (1.4% vs 30.7%, P<0.05). Supplementation of culture medium with 0.34 mmol/L pyruvate and 5.4 mmol/L lactate from 0 to 60 hours increased the cleavage rate of porcine embryos (71.0% vs 63.9%, P<0.05), but the blastocyst formation rate was decreased significantly when pyruvate and lactate were present in the culture medium after 60 h of culture (3.0, 6.3, 3.3% vs 20.2%, P<0.01). Culturing embryos with glucose from the beginning of culture improved the blastocyst formation rate significantly (20.1% vs 10.3%, P<0.05). Addition of 12 mmol/L sorbitol to NCSU-23 medium resulted in an increase in the blastocyst formation yield (32.4% vs 26.0%, P=0.1875).In conclusions, (1) Supplementing NCSU-23 medium with BSA was better than with FCS in culture of porcine embryos; (2) Complex culture medium is unsuitable to culture porcine embryos; (3) Hypotaurine is an important component for porcine embryo culture and its concentration can be declined to 0.5 mmol/L; (4) Pyruvate and lactate are benefit to the early porcine embryo development but detrimental to the subsequent development, glucose is benefit to porcine embryo development in whole period of in vitro culture; (5) Sorbitol may promote the porcine embryo development, which will need to be confirmed further.