The developmental capacity of bovine oocytes under three different culture systems was investigated in this experiment ; One was culture in TCM199 with bovine oviductal epithelial cells (BOEC) for in vitro culture, another was culture in TCM199 with BOEC for 2 days and then transfer of 4∼8cell embryos to rabbit oviduct(RO) and the other was transfer of 1 or 2ce11 embryos to RO for in vivo culture. And the other concern of this experiment was to investigate the effect of culture period and transfer site on recovery.
Immature bovine oocytes were cultured in TCM199 with granulosa cells for 22-24hrs and then fertilized in vitro using frozen-thawed semen treated with BO-caffine and BO-BSA. Fifteen to 18hrs after in vitro fertilization oocytes were cultured in TCM199 with BOEC or transferred to RO for 5 days.
The rate of development to the morula or blastocyst was higher in transfer of 1 or 2cell embryos to RO (23.1%) than culture in TCM199 with BOEC (11.7%). E>ut, there was no difference between transfer of 1 or 2cell embryos and transfer of 4∼8cell embryos to RO (12.8%). Recovery under different culture periods in RO was significantly higher in 90∼95hrs(70.1%) than 122∼125hrs(50.9%, p<0.05) and recovery significantly increased when oocytes were transferred deeper in RO(2.5cm>, 47.7% ; 2.5∼4.5cm, 63.9%; 4.5cm<, 77.3%, p<0.05).
The results show that transfer of 1 or 2cell embryos to RO is an effective means of supporting the further development of in vitro matured and fertilized bovine oocytes than culture in TCM199 with BOEC or transfer of 4∼8cell embryos to R0, and recovery from RO increases when oocytes are transferred deeper and incubated shorter in RO.
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