Abstract
The purpose of this study was to investigate the effects of embryo sources such as in vivo vs. in vitro produced blastocyst, and culture systems on the membrane permeability and viability of bovine blastocyst following GMP vitrification. To produce in vivo embryos, six cows were superovulated by administration of follicle stimulation hormone (FSH) and prostaglandin $F_{2{\alpha}}$(PG $F_{2{\alpha}}$). in vitro embryos were produced by two different culture systems, oviduct co-culture (OCS) and defined culture system (HECM-6; DCS). Ovaries were picked up at a local slaughterhouse and transported to laboratory in 3$0^{\circ}C$ saline within 2 h. Ovaries were washed with same saline three times and then placed in saline on warm plate adjusted at 3$0^{\circ}C$ during aspiration. The blastocysts produced were assigned for membrane permeability and viability following GMP vitrification. The membrane permeability of blastocysts was checked in 0.5 M sucrose solution on warm plate at 35$^{\circ}C$ for 0, 2, 5 and 7 min, respectively. Then the diameters (width and length) of embryo cytoplasms were measured by a eyepiece meter, and they were converted to their volume by 4/3 $\pi$ $r^3$. The blastocysts were cryopreserved by GMP vitrification method, where they were sequentially placed into vitrification solution before being loaded into GMP vessels and immersed into L$N_2$ within 20 to 25 sec. Post-thaw blastocysts were serially washed in 0.25 and 0.15 M sucrose in HM and TCM-199 for 5 min each, and then cultured in TCM 199 supplemented with 10% FCS for 24 or 48 h. The volume change of in vivo blastocyst at 0, 2, 5 and 7 min (100, 37.1, 34.3 and 31.6%) was significantly more shrunk than those of in vitro blastocysts derived from OCS (100, 59.8, 48.9, 47.9%) and DCS (100, 57.2, 47.3 and 46.9%) (P＜0.05). The viability of post-thaw blastocyst derived from in vivo (93.6%) was also significantly different from those in OCS and DCS (81.9 and 83.6%; P＜0.05). In the present culture system, the morphology of embryos produced in vitro was similar to that of in vivo embryos, but the quality in membrane permeability and post-thaw viability showed a big difference from their sources as in vivo or in vitro derived from OCS and DCS. The results indicated that the quality of in vivo embryos in membrane permeability and post-thaw viability was better than those of in vitro embryos derived from OCS or DCS.
본 연구는 체내, 체외수정란 및 배양체계가 세포막투과력 및 GMP vitrification후 생존성에 미치는 영향을 조사하고자 실시하였다. 체내수정란은 6마리 한우를 FSH와 PG $F_{2{\alpha}}$ 에 의한 과배란처리하여 생산하였다. 체외수정란은 난관상피세포 공배양 (OCS) 및 HECM-6 (DCS) 방법으로 생산하였다. 생산된 배반포기 배는 세포력투과력과 GMP vitrification 후 생존성의 조사를 위하여 사용되었다. 세포력투과력은 35$^{\circ}C$ 가온판과 0.5 M sucrose 용액에서 0, 2, 5 및 7분간의 노출시간에 세포질의 “가로 $\times$ 세로”의 직경을 조사하였다. 세포질의 용적은 조사한 직경을 4/3.$\pi$ $r^3$ 공식으로 계산하였다. 배반포의 동결보존은 GMP vitrification 방법으로 실시하였으며, 융해 후 0.25와 0.15 M sucrose 용액 및 TCM199에 각각 5분간 세척한 후 TCM199에 24 또는 48시간동안 배양하였다. 체내수정란의 0, 2, 5 및 7분 때의 용적변화(100, 37.1, 34.3 및 31.6%)는 OCS(100, 59.8, 48.9 및 47.9%)와 DCS(100, 57.2, 47.3 및 46.9%) 보다 유의적으로 높게 수축되었다(P＜0.05). 또한 체내수정란(93.6%)의 동결융해 후 생존성은 OCS 및 DCS (81.9 및 83.6%) 보다 유의적으로 높았다(P＜0.05). 현 배양체계에서 체외수정란의 형태는 체내수정란과 유사하였지만, 세포막투과력 및 응해 후 생존성 등의 질적인 면에서는 큰 차이를 보였다. 결론적으로 세포력 투과력 및 동결융해 후 생존성 등의 질적인 면에서 체내수정란은 OCS 또는 DCS 배양체계에서 생산된 체외수정란보다 우수하였다.