In Vitro Fertilization of Pig Oocytes Matured In­Vitro by liquid Boar Spermatozoa

The present study was carried out to investigate the effects of the maturation media such as a modified TCM-199 (mTCM-199) medium, modified Waymouth MB 752/1 (mWaymouth MB 752/1) medium or NCSU-23 medium on penetrability of pig oocytes by liquid boar sperm. Oocytes (30~40) were transferred into each well of a Nunc 4-well multidish containing 0.5 $m\ell$ maturation medium. When immature pig oocytes were cultured in mTCM-199, mWaymouth MB 752/1 and NCSU-23 maturation media for 44 h in 5% $CO_2$, in air at 38.5$^{\circ}C$, the germinal vesicle breakdown (CVBD) rates of the oocytes were 95.6, 94.1 and 94.9%, respectively, and the maturation rates (metaphase II) of oocytes were 92.5, 90.1 and 91.1%, respectively. No differences were observed among the maturation media. The spermrich portion of ejaculates with greater than 90% motile sperm were used in the experiment. The semen was cooled 22 to 24$^{\circ}C$ over 2 h period. The semen was diluted with Beltsville Thawing Solution (BTS) extender at room temperature to give 2$\times$10$^{8}$ sperm/$m\ell$ in 100 $m\ell$ plastic bottle. Liquid boar semen of 30 $m\ell$ in 100 $m\ell$ plastic bottle was kept at 17$^{\circ}C$ for 5 days. The sperm with greater than 70% motility after day 5 of storage were used for in-vitro fertilization (IVF). After 44 h maturation of immature oocytes, cumulus cells were removed and oocytes (30~40) coincubated far 6 h in 0.5 $m\ell$ mTCM-199 and mTBM fertilization media with 2$\times$1061$m\ell$ sperm concentration. At 6 h after IVF, oocytes were transferred into 0.5 $m\ell$ mTCM-199 and NCSU-23 culture media for further culture 6 or 42 h. Sperm penetration, polyspermy and male pronuclear formation of oocytes at 12 h after IVF, and developmental ability of oocytes at 48 h after IVF were evaluated. The oocytes in combination with NCSU-23 medium for maturation and mTBM medium for IVF increased male pronuclear formation (48.0%) compared to those in combination with mTCM-199 media for maturation and IVF, and mWaymouth MB 752il medium for maturation and mTCM-199 medium far IVF. The rates of cleaved embryos (2~4 cell stage) at 48 h after IVF were 24.1% in combination with mTCM-199 media for maturation, IVF and culture, 43.6% in combination with mWaymouth MB 75211 medium fur maturation and mTCM-199 media for IVF and culture, and 71.2% in combination with NCSU-23 medium for maturation, mTBM medium for IVF and NCSU-23 medium for culture. In conclusion, we found out the oocytes matured in vitro were fertilized by liquid boar sperm stored in BTS extender at 17$^{\circ}C$ for 5 days. We recommend the simple defined NCSU-23 medium for nuclear maturation, mTBM medium and liquid boar sperm for IVF, and NCSU-23 medium for embryo culture.

체외성숙 돼지 난포란의 액상정액을 이용한 체외수정

본 연구는 지금까지 돼지 난포란 성숙을 위해서 많이 사용하고 있는 mTCM-199, mWaymouth MB 752/1 그리고 NCSU-23 성숙배지를 비교하고 액상정액을 이용한 체외수정 방법을 개발하고자 실시하였다. 미성숙 난포란은 0.5 $m\ell$의 성숙배지에 각 well 당 30~40개씩 적하하였고, 38.5$^{\circ}C$, 5% CO2, 95% 공기로 조절된 CO2 배양기에서 44시간 성숙 시켰다. 미성숙 난포란을 mTCM-199, mWaymouth MB 752/l 그리고 NCSU-23 성숙배지에서 44시간 배양한 결과 CVBD 발생율은 각각 95.6, 94.1 그리고 94.9%였으며, MH단계까지의 성숙율은 각각 92.5, 90.1 그리고 91.1%였다. 성숙배지별, GVBD 발생율과 MH까지의 성숙율간에 유의성은 인정되지 않았다. 액상정액의 제조용 정액은 90% 이상의 운동성을 가진 농후정자부분을 사용하였으며 정액 채취 후 2시간 동안에 22~24$^{\circ}C$의 실온까지 냉각시켰다.실온까지 냉각한 정액은 BTS 희석액으로 2$\times$$10^{8}$ $m\ell$ 정자농도로 조정하여 100 $m\ell$ 플라스틱병에 30 $m\ell$씩 주입하여 17$^{\circ}C$에서 5일간 보관하였다. 5일 보관 후 운동성이 70% 이상인 정자를 체외수정에 이용하였다. 성숙 후 cumulus cell들이 제거된 성숙난포란은 0.5 $m\ell$의 mTCM-199 또는mTBM 수정배지에 30~40개씩 적하하고, 최종정자농도를 2$\times$$10^{6}$$m\ell$되도록하여 6시간 동안 수정시켰다. 체외수정시킨 수정란들은 0.5 $m\ell$의 NCSU-23 배양배지에서 수정 후 6시간 배양하여 정자침입율, 다정자침입율 그리고 웅성전핵형성율을 조사하였고, 수정 후 45시간 배양하여 난할율을 조사하였다. NC-SU-23 성숙배지와 mTBM 수정배지를 이용하였을때 웅성전핵형성율이 48.0%로써 mTCM-199 성숙배지와 수정배지 또는 mWaymouth MB 752/1 성숙배지와 mTCM-199 수정배지를 이용하였을 때보다 웅성 전핵 형성율이 높았다. 2~4세포기까지의 난할율은 mTCM-199 성숙, 수정 및 배양배지에서 24.1%, mWaymouth 752/1 성숙배지, mTCM-199 수정 및 배양배지에서 43.6%, 그리고 NCSU-23 성숙배지, mTBM 수정배지 및 WCSU-23 배양배지를 이용한 것이 71.2%였다. 이상의 결과를 종합하면 BTS 희석액으로 17$^{\circ}C$에서 5일 보존한 액상정액으로 체외수정이 가능함을 입증하였고, NCSU-23 성숙배지, mTBM 수정배지 및 NCSU-223 배지가 미성숙 난포란의 성숙, 수정 및 배양에 우수한 배지임을 입증하였다.