본 연구는 난자의 성숙시간, PHA-P 처리 또는 활성화 방법이 소 미수정란의 탈핵, 재구축란의 융합, 활성화 또는 체외발육에 미치는 영향을 검토하였다. 미수정란은 성숙 후 16∼24시간에 탈핵을 실시하고, PHA-P 처리 또는 무처리된 귀 피부세포를 이식 후 전기융합을 실시하였다. 후자의 경우는 융합 전에 PHA-P로 15분간 배양하였다. 융합란은 A23187과 CHXM 혹은 DMAP의 병용처리에 의해 활성화를 유기하고, 7∼9일간 체외배양하였다. 탈핵율은 성숙 후 16∼18시간에 실시한 경우(70.2∼92.3%)가 성숙 후 20∼24시간(44.3∼3.4%)에 비하여 유의적으로 높았다(P<0.05). M-II기 염색체의 위치는 성숙배양 시간이 길어짐에 따라 제 1 극체와의 간격이 멀어졌다. Donor 세포 혹은 재구축란에 PHA-P를 처리한 경우는 무처리구에 비하여 융합율이 향상되었다(P<0.05). 핵이식배의 분할율 및 배반포 발달율은 A23187+DMAP 처리구에서 78.6%와 32.9%로, A23187+CHXM 처리구에 비하여 유의적으로 높았다(P<0.05). 본 실험 결과는 성숙후 18시간에 탈핵을 실시하는 것이 효과적이며, donor세포 또는 융합 전 재구축란의 PHA-P 처리가 융합율 향상시킬 수 있고, 또한, 융합란을 A23187과 DMAP으로 병용처리 함으로써 난자의 활성화 및 배반포 발육율을 향상시켜, 결과적으로 핵이식기술의 효율성을 증진시킬 수 있을 것으로 사료된다.

This study was conducted to investigate the effects of quiescent treatment of donor cells and activation treatment time of recipient cytoplasm on nuclear remodeling and in vitro development of somatic cell-cloned bovine embryos. Serum starved, confluent and nonquiescent cycling adult skin cells were teansferred into enucleated oocytes. Nuclear transfer oocytes were activated at 30 min, 1 and 2 hrs after electrofusion. Some nuclear transfer embryos(23% to 35%) extruded a polar body, which was not affected by quiescent treatment of donor cells and activiation time of recipient cytoplasm. About 68% of nuclear transfer embryos fused with a serum starved cells has a chromatin clump, but which was not different from embryos fused with confluent(51%) and nonquiescent(47%) cells. The proportion of embryos with a single chromatin clump was sightly increased when nuclear transfer embryos were activated within 30 min after fusion(69%) compared to those were activated at 1 and 2 hrs after fusion, but there was not significantly different. Development rates to the blastocyst stage were 8.6% and 15.9% when serum starved and confluent cells were transferred, which were higher than that of control group. Developmental rate to the blastocyst stage was higher in embryos were activated within 30 min after fusion (17.3%) compared to those of embryos were activated at 1 and 2 hrs after fusion (P<0.05). From the present result, it is suggested that quiescent treatment of donor cells and activation time of recipient cytoplasm can affect the in vitro development. Quiescent plasm activation within 30 min after fusion could increase the number of embryos with a normal chromation structure, which results in increased in vitro development.