ICM - Trophectoderm Cell Numbers of Mouse IVF/IVC Blastocysts

체외생산된 생쥐 배반포기배의 ICM과 Trophectoderm 세포수에 관한 연구

This work has been carried out to examine the number of Total, ICM and TE cells of F1 mouse blastcysts at day 4 after IVF by differential labelling of the nuclei with polynucleotide-specific fluorochromes and to obtain a fundamental information of preimplantation mouse embryo development. Blastocysts produced by superovulated B6CBA F1(C57BL/${\times}$CBA) eggs were inseminated with $1{\times}10^6$spermatozoa/ml and cultured in M16 medium at $37^{\circ}C$, 5% $CO_2$ incubator for 95hrs. Blastocysts were classified as early, middle, expanded and hatching stage according to the developmental morphology; blastocoel expansion and zona thickness. The results obtained in these experiments were summarized as follows; 1) The development rate of blastocysts at 95hrs after IVF was 86.7% and classified blastocysts to early, middle, expanded and hatching were 16.3%, 18.9%, 10.5% and 40.9%, respectively. 2) The numbers of total blastomere using bisbenzimide in the classified blastocysts to early, middle, expanded and hatching were 35.6${\pm}$1O.4, 49.4${\pm}$8.6, 60.8${\pm}$1O.7 and 62.7${\pm}$13.9, respectively. 3) In ICM and TE cell number by using differential labelling with polynucleotide-specific fluorochrome in the classified blastocysts to early, middle, expanded and hatching; ICM numbers were 9.6${\pm}$3.0, 13.6${\pm}$3.9, 16.0${\pm}$3.3 and 19.5${\pm}$4.6, respectively and TE cell numbers were 30.6${\pm}$5.1, 39.9${\pm}$5.8, 42.2${\pm}$8.1 and 43.7${\pm}$11.1, respectively. These results showed the same increase pattern according to development advance level. Also, when compared with the results of total count were obtained between bisbenzimide only and differential labelling, both of them showed the same increase pattern according to development level and at the same time their cell numbers were almost the same. So, rapid and simple cell count method using differential labelling can be used for the examination of later preimplantation development or as an indicator of embryo quality according to the variables of culture conditions.

본 연구는 Polynucleotide-specific 형광물질을 이용한 Differential labelling 기법으로 체외수정 후 배양 4일째 생산된 B6CBA Fl 생쥐 배반포의 Total, ICM, Trophectoderm의 세포수를 조사함으로서 생쥐의 착상전 후기 배발달에 대한 기초 자료를 얻고자 실시하였다. 공시 배반포는 과배란처리에 의해 얻어진 난자를 $1{\times}10^6cells/ml$의 정자로 수정시키고, 95시간동안 M16배양액과 $37^{\circ}C$, 5% $CO_2$배양기 내에서 배양하여 배반포강의 확대와 투명대 두께의 감소를 기준으로 early, middle, expanded와 hatching으로 구분하였다. 본 연구에서 얻어진 결과는 다음과 같다. 1) 체외수정 후 95시간째 배반포 발달율은 86.7%였으며, early, middle, expanded와 hatching으로 16.3%, 18.9%, 10.5%, 40.9% 였다. 2) Bisbenzirnide를 이용한 배반포의 총 세포수는 early, middle, expanded, hatching 각각 $35.6{\pm}10.4$, $49.4{\pm}8.6$, $60.8{\pm}10.7$ 과 $62.7{\pm}13.9$를 얻었다. 3) Polynucleotide-specific형광물질을 이용한 Differential labelling으로 배반포 ICM과 Trophectoderm의 세포수를 early, middle, expanded, hatching으로 나누어 조사한 결과, ICM세포수는 각각 $9.6{\pm}3.0$, $13.6{\pm}3.9$, $16.0{\pm}3.3$, $19.5{\pm}4.6$개 이었고, Trophectoderm세포수는 $30.6{\pm}5.1$, $39.9{\pm}5.8$, $42.2{\pm}8.1$, $43.7{\pm}11.1$ 개로 나타나 ICM과 Trophectoderm 모두 동일하게 발달의 진행정도에 따라 세포수의 증가양상을 나타내었다. 또한, Bisbenzimide와 Differential labelling에서 얻어진 총세포수의 비교에서도 동일하게 발달의 진행정도에 따라 세포수의 증가를 나타내었으며 그와 동시에 세포수도 거의 유사하였다. 이러한 결과로 미루어 볼때, Differential labelling을 이용한 빠르고도 간편한 세포수 계산법은 착상전 후기 배발달을 고찰하는데 유용하며, 배양조건에 따른 Embryo의 Quality를 반영하는 Indicator로서 이용될 수 있다는 것을 시사한다.