| 1. Parthenogenetic activation of rabbit oocytes was investigated in this study. The cleavage rate of oocytes activated in 7% ethanol for 5 min (13.0%) were significantly lower than that of oocytes activated in 7% ethanol (48.1%) or 5 \unao\JL ionomycin (92.2%) for 5 min following in 5mmol/L DMAP for 3 h. The percentage of cleaved oocytes developing to blastocysts (27.1%)was also significantly higher (P<0.05) when oocytes actvated in ionomycin and DMAP, in comparison with oocytes activated in ethanol alone (0%) or ethanol plus DMAP (15.4%). When oocytes were activated using ionomycin and DMAP at 18 h after hCG injection, 92.1% of oocytes cleaved and 35.3% of cleaved oocytes developed to blastocysts, which were significantly higher than that of oocytes activated beyond 24 h post-hCG injection (19.0% and 4.2% resp, p<0.05). Three hours was proved to be appropriate for oocytes culturing in DMAP after ionomycin treatment, in which 88.6% of oocytes cleaved and 34.2% of cleaved oocytes developed to blastocysts, which was higher than that of oocytes culturing in DMAP for 1 h (86.1% and 28.3% resp) or 5 h (72.6% and 26.4% resp). Additional electronic pulse to oocytes activated using ionomycin and DMAP did not affect their cleavage rate (83.3% vs 80.0%) and blastocyst development (30.0% vs 27.0%). Exposure of oocytes to cytochalasin B (5mg/L) for 20 min prior to ionomycin and DMAP treatment also did not influence their subsequent cleavage rate (86.0% vs 83.3%) and blastocysts developed (36.7% vs 33.3%).2. The change of rabbit oocyte spindles in different condition was measured, and different methods for enucleation of oocytes were also compared in this study. Results indicate that the Piezo-driven system can reduce the mechanical damage to oocytes, and then improve the survival rate of oocytes after enucleation up to 98.0%. The space between nuclear and the first polar body increase as the oocyte aged, the proportion of oocytes with the first polar body near to spindle deceased from 70.4% to 60.5% when the age of oocytes increased from 16h to 19h post-hCG injection; The spindle view system can significantly increase the enucleation efficiency (98.4%), compared with the blind enucleation method (83.8%, P<0.05). The optimum age for enucleation was proved to be 19h post-hCG injection, and the optimum temperature of manipulation was proved to be36~37癈.3. Factors affecting the efficiency of nuclear transfer in rabbits were examined in the present study. When 100 v/mm of pulse intensity and 15 us of pulse duration were employed, 3 and 4 electronic pulses resulted in significantly more cytoplasts fused with donor cells (81.7% and 85.5% resp) compared with 2 electronic pulses (64.1%, P<0.05),42but no significant difference was found in the cleavage rate of reconstructed embryos among the three groups (77.4%, 84.9% and 80.0% resp, P>0.05). When the duration and number of electronic pulse were fixed at ISjis and 3, increase of pulse intensity from 100 v/mm to 150 v/mm and 200 v/mm resulted in a significantly decrease in the cleavage rate of reconstructed embryos (76.9% vs 56.5% and 57.6% resp, P<0.05), although the fusion rate did not significantly differ among the three groups (79.4%, 82.1% and 86.8% resp, P>0.05). Significantly more reconstructed embryos cleaved (79.8%) and developed to blastocysts (24.0%) when they were derived from donor embryos at the 8-16 cell stage, in comparison with the reconstructed embryos derive from donor embryos at the compact morula stage (66.7% and 9.8% resp, P<0.05), although the fusion rate was similar (76.3% vs 75.0, P>0.05). Activation of cytoplasts prior to fusion increased the cleavage rate (84.0% vs 62.0%, p<0.05) and blastocyst development (33.6% vs 21.0%, P<0.05) of reconstructed embryos, but decreased the fusion rate (9.8% vs 95.2%, P<0.05), compared with cytoplasts activated post fusion. More reconstructed embryos developed to blastocysts (33.6%) when they were cultured in TCM-|-3%OCS at the first 48h and then cultured in TCM199 + 10%FCS, in comparison with the recon...
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