Abstract
This study was carried out to investigate the in vivo developmental potential of mouse zona-hatched blastocysts (HBs). The HBs were cultured in vitro until day 5 and day 6 from zygotes produced in vivo and classified to small (S-HBs), medium (M-HBs) and large (L-HBs) on the basis of embryo diameters. The results obtained in these experiments were summarized as follows ; 1) when the blastocysts at day 4 were further cultured for $24\sim48hr$, HBs obtained at day 5 and day 6 culture in vitro were 29.1% and 22.8%, respectively. 2) Also, when the total cell number of HBs were counted, cell numbers of classified HBs on day 5 and day 6 to small ($77.3\pm5.3$, $59.6\pm4.4$), medium ($83.7\pm4.0$, $66.8\pm3.5$) and large ($100.7\pm2.6$, $88.9\pm3.8$) were increased as their size increases. Especially, there were significantly different between S-HBs and L-HBs (p<0.01). 3) In addition, when the classified HBs were transferred into when the classified HBs were transferred into day 3 pseudopregnant recipients, the pregnancy and implantation rates of S-HBs (28.6%, 15.7%), M-HBs (44.4%, 30.9%) and L-HBs (62.5%, 49.1%) at day 5 were increased as their size increases. However, this pattern was not showed in embryo transfer of day 6 HBs. But, when the live fetuses formation against total implantation rates were observed, the result (87.5%) of S-HBs of day 5 was significantly higher than that of the others (p<0.01). Therefore, this study demonstrates that in vitro cultured healthy HBs can not only be developed normally with good pregnancy rates, implantation rates and live fetuses formation, but also served as a fundamental data for utility of supernumerary HBs in human blastocyst transfer.
본 연구는 생쥐 완전탈출 배반포기배의 체내 발달율을 조사하기 위해 실시하였다. 공시된 완전탈출 배반포기배는 체내에서 생산된 전핵기 수정란을 5일과 6일동안 체외배양하여 얻었으며, 완전탈출 배반포기배의 직경을 기준으로 small(S-HBs), medium(M-HBs), large(L-HBs)로 구분하였다. 그 결과를 요약하면 다음과 같다. 1) 체외배양 4일째에 얻어진 배반포기배를 $24\sim48$시간동안 추가배양했던 바, 배양 5일과 6일째에 완전탈출 배반포기배의 발달율은 29.1%와 22.8%였다. 2) 또한, 완전탈출 배반포기배의 총 세포수를 조사하였던 바, S-HBs ($77.7\pm5.3$, $59.6\pm4.4$), M-HBs ($83.7\pm4.0$, $66.8\pm3.5$), L-HBs ($100.7\pm2.6$, $88.9\pm3.8$)로 나타나, 완전탈출 배반포기배의 크기가 증가함에 따라 총 세포수도 증가한다는 것을 알 수 있었다. 특히, S-HBs와 L-HBs의 총 세포수간에는 유의적인 차이가 있었다.(p<0.01). 3) 분류된 완전탈출 배반포기배를 가임신 3일된 대리모의 자궁에 이식하였을 때, 배양 5일째의 임신율과 착상율이 S-HBs (28.6%, 15.7%), M-HBs (44.4%, 30.9%), L-HBs (62.5%, 49.1%)로서 완전탈출 배반포기배의 크기가 커질수록 증가하였던 반면, 배양 6일째에는 이러한 양상을 볼 수 없었다. 그러나, 전체 착상율에 대한 정상산자율을 조사하였던 바, 배양 5일째의 S-HBs (87.5%)가 다른 군에 비하여 유의하게 높게 나타났다. (p<0.01). 따라서, 이러한 결과로 미루어 볼 때, 체외에서 배양된 건강한 완전탈출 배반포기배는 높은 임신율과 착상율 및 정상산자율을 얻을 수 있음을 확인하였던 바, 이는 인간포배기 배아이식시 잉여의 완전탈출 배반포기배의 유용성 검토를 위한 기초자료로서 이용될 수 있음을 시사한다고 하겠다.
