Abstract: The aim of this research was to investigate the effect of cytochalasin B (CB) on the developmental ability of parthenogenetic embryos and cloned embryos in pigs.The optimal concentration and incubation time of CB on early porcine embryo development were screened out by testing different concentrations and treatment time of CB in porcine in-vitroembryo culture medium.At the same time,Hoechst33342 staining was used to observe the difference in cell number of porcine blastocysts during incubation,to study the effect of CB on the development of parthenogenetic embryos and cloned embryos.The results showed that the cleavage rates of parthenogenetic embryos and cloned embryos incubated with 7.5 μg/mL CB in standard culture conditions were 85.00% and 90.23%,respectively,and the blastocyst rates were 35.68% and 42.58%,which were significantly higher than other groups (P < 0.05);While the cleavage and blastocyst rates of the parthenogenetic embryos for 4 h group were 83.80% and 35.39%,and the cloned embryos form cleavage and blastocyst for 6 h group were 83.98% and 55.62%,there were significant differences by corresponding to other groups (P < 0.05),respectively.In addition,embryos stained with Hoechst33342 showed that the average number of parthenogenetic embryos inner cells without CB were 28,and inner cells average numbers in the parthenogenetic and cloned embryos with CB were 36 and 52.There was a significant difference in the number of inner cells between the treated and untreated groups (P < 0.05).The results showed that the parthenogenetic embryos in vitro were treated for 4 h with 7.5 μg/mL CB,which resulted in higher cleavage and blastocyst rate;and the cloned embryos in vitro were treated for 6 h with 7.5 μg/mL obtained the highest of the cleavage and blastocyst rate.The results showed that CB treatment was beneficial embryo early development in vitro and improved the pregnancy rate of cloned embryos.

Key words: cytochalasin B; parthenogenetic embryo; cloned embryo; blastocyst