본 연구는 토끼난자에 있어서 배란 후 경과시간에 따른 탈핵률을 조사하고 ionomycin과 DMAP을 사용하여 활성화와 아울러 자체 탈핵을 유도하는 방법을 고안하였으며 아울러 이들의 탈핵효율과 핵이식후 체외발달을 확인한 결과는 다음과 같다. 1. hCG 주사후 15∼16 시간에 채란된 토끼난자는 73.4%의 탈핵률을 보였고, 16∼17시간에는 75.8%, 19∼20 시간에는 58.5%의 탈핵률을 보여 토끼난자의 탈핵은 hCG 주사후 17시간 이내에 실시
Enucleation of oocytes is an important limiting step for embryo cloning. We propose an enucleation technique based on the removal of chromatin after oocyte activation by aspirating the second polar body containing complemented chromatin. In a preliminary experiment to determine an optimal age of oocytes enucleation in rabbits, oocytes were enucleated at 15~20 hours post hCG. Recently ovulated oocytes were enucleated at a higher rate than aged oocytes. Microsurgical removal of the complemented chromatin in the second polar body was significantly more effective in enucleating than aspiration of a larger cytoplasm volume surrounding the first polar body of metaphase-arrested oocytes(96.8% versus 70.4%; P〈0.05). Moreover, compared with a nuclear transplantation protocol based on enucleation of metaphase-arrested oocytes and preactivated oocytes followed by treatment with 5 M ionomycin for 5 min and 2 mM DMAP for 1 hr, there was no significant difference in the rate of blastocyst development. The ease with which modified technique can be performed is likely to render this technique widely useful for research and practice on mammalian cloning.