RESUMO
Objective To investigate an appropriate activation method and culture system in vitro of rabbit parthenogenetic embryos to make an experimental foundation for therapeutic cloning.Methods Mature rabbit oocytes with polar body 1 (PB 1) were divided randomly into four groups and accepted,respectively,parthenogenetic activation with 1.2 kV/cm,1.6 kV/cm and 2.0 kV/cm electricity stimulation or 5 μg/mL ionomycin (ION) chemical treatment; the effects of these different treatments on activation efficiency were compared.The activated oocytes were cultured,respectively,in M199 supplemented with various concentrations of leukaemia inhibitory factor (LIF,0,10,20,40 and 80 ng/mL) or insulin+transferrin+sodium selenite (ITS,0×,1 × and 2×); and then,the rate of cleaved oocytes,percentage of morulas/blastocysts and total number of blastocysts were compared between each two groups.Results (1) Different treatments on the oocytes showed significantly different activation effects.The survival rate of oocytes activated in 5 μg/mL ION for 4 min were significantly higher than that of ones stimulated by 2.0 kV/cm electricity treatment (P=0.016).The percentages of cleaved oocytes,developing 8-16 cells and morulas/blastocysts in the ION treatment group were also significantly higher as compared with those in the 1.2 kV/cm electric treatment group (P=0.000,P=0.002 andP=0.026,respectively).(2) Significant difference in the percentage of morulas/blastocysts was noted between 20 ng/mL and 80 ng/mL of LIF supplementation (P=0.003); in addition,the total number ofblastocysts in the medium supplemented with 20 ng/mL LIF was significantly different to those with 40 ng/mL and 80 ng/mL,respectively (P=0.011,P=0.002); In experiment of ITS supplementation,significant difference in the percentage ofmorulas/blastocysts was shown between 1 × and 2× ITS supplementation (P=0.003); in addition,the total number of blastocysts in the medium supplemented with 0× or 1 × ITS (166 and 147 cells) was significantly different as compared with that with 2× ITS (78 cells,P=0.015,P=0.044).Conclusion The parthenogenesis activation of the New Zealand rabbit's oocytes treated with ION+6-DMAP shows a higher rate of cleaved oocytes and blastocysts than that with electricity stimulation; the subsequent development of parthenogenetic embryos in vitro could be significantly improved by supplementing with 20 ng/mL LIF and 1× ITS.