Abstract
This experiment was designed to evaluate the effect of transforming growth factor-$\beta$ (TGF-$\beta$) and insulin-like growth factor-I (IGF-I) in bovine oocyte maturation in the presence or absence of serum on subsequent fertilization and embryo development. In addition, various concent rations of these growth factors were evaluated for the ability to promote development of eight-cell stage embryos to the blastocyst stage. Cumulus-oocyte complexes were recovered from 2 to 6 mm follicles obtained from slaughterhouse ovaries and cultured at 38.5$^{\circ}C$ for 24 hours in TCM-199 (HEPES Modification) with or with out 20 % fetal bovine serum (FBS) to which the following growth factors were added TGF$\beta$ IGF-l or TGF $\beta$ + IGF-I, all at 10 ng/ml each. The matured oocytes were fertilized in IVF-TL medium with frozen-thawed semen at a concentration of 1 ${\times}$ 10$^6$ cells/ml of fertilization medium following Percoll separation. After 24 hours of sperm-egg incubation, the embryos were transferred to CZB medium without glucose for 48 hours and then cultured in TCM-199 with 20% fetal bovine serum (FBS) for 96 hours. The addition of growth factors to IVM medium in the presence of serum had no effect on cleavage and subsequent embryo devlopment to blastocyst. In the absence of serum, TGF- improved cleavage and development to blastocyst compared to control's(p<0.05) and no synergistic effeet of IGF-I + TGF-$\beta$ was observed. In the second experiment, eight-cell embryos obtained by in vitro maturation (IVM) in TCM-199 + 20% FBS without growth facrors and in vitro fertil-ization (IVF) were cultured in the in vitro cuiture (IVC) medium supplemented with 5, 10 ng/ml TGF-$\beta$ or 5, 10, 50, 100 ng/ml IGF-I. Cleavage rate and development to the blastocyst stage was observed during seven days of incubation. The supplementation of 10 ng/ml TGF-$\beta$ to lVC medium for eight-cell embryos improved development to blastocyst (p<0.05) compared to control. In conclusion, these data indicate that the supplementation of growth factors to IVM medium in the presence of serum does not influence cleavage and subsequent embryo development. However, significantly more oocytes matured in serum-free TCM-199 and eight-cell embryos cultured in lVC medium developed to blastocyst with supplementation of 10ng/ml TGF-$\beta$.
본 연구는 혈청첨가 또는 무첨가에 따른 소 난포란의 체외성숙에 있어서 참가된 TGF-$\beta$1과 IGF-I이 그후의 수정 및 발생에 미치는 영향과, 이들 growth factor의 농도에 따른 8세포기 소 체외수정란의 발달에 미치는 영향을 조사하고자 실시하였다. 도축장에서 얻어진 난소로부터 채취된 난포란을 20% FBS가 첨가 또는 첨가되지 않은 TCM-199에 TGF-$\beta$1, IGF-I 또는 TGF-$\beta$1＋IGF-I을 각각 10ng/ml 첨가하여 38.5$^{\circ}C$에서 24시간 배양하여 체외성숙을 유기하였다. 성숙된 난자를 1$\times$106/ml 정자농도로 수정후 24시간에 glucoserk 첨가되지 않은 CZB 배양액으로 옮겨 48시간 배양한 다음, TCM-199＋20%FBS에서 96시간 추가배양하였다. 본 연구에서 혈청이 첨가된 난포란의 체외성숙배양액에 첨가된 growth factor들은 수정후의 배분할 및 배발생에 영향을 미치지 않았다. 혈청이 첨가되지 않은 경우에서는 TGF-$\beta$1의 첨가는 배분할 및 배발생율을 향상시켰다(P<0.05). 한편 TCM-199＋20%FBS에 5, 10ng/ml의 TGF-$\beta$1 및 5, 10, 50, 100ng/ml의 IGF-I을 각각 첨가후 8세포기 체외수정란을 배양한 결과, 10ng/ml TGF-$\beta$1의 첨가는 배반포기로의 발생율을 향상시켰다(P<0.05). 결론적으로, 혈청이 포함되지 않은 소 난포란의 체외성숙 배양액, 또는 수정란의 체외배양액에 10ng/ml TGF-1의 첨가는 배반포기로의 발생율을 향상시킨다.