개 난자의 체외성숙율을 높이기 위하여 다양한 방법들이 시도되고 있지만 여전히 그 효율성은 낮다. 본 연구는 개 난자의 체외성숙 시, 성선 자극 호르몬인 황체형성호르몬(LH)과 난포자극호르몬(FSH), 상피세포성장인자(Epidermal growth factor, EGF) 그리고 시스테인(cysteine)을 각각 첨가하여 72시간 동안 체외성숙시킨 후 핵성숙율(GV: germinal vesicle, GVBD: germinal vesicle break down, MI: metaphase I, MII: metaphase II, UK: unknown stage)을 확인하였다. LH와 FSH를 첨가하였을 때 첨가하지 않은 군과 GV, MI 및 MII율에는 유의적인 차이는 없었다. 하지만 GVBD율은 첨가군이 유의적으로(p<0.05) 높았다. 성선 자극 호르몬을 첨가한 배지에 10 ng/ml의 EGF를 첨가하였을 때 MII율이 첨가하지 않은 군보다 유의적으로(p<0.05) 높았다(4.54% vs. 7.06%). cysteine을 첨가하였을 경우, 핵성숙율에 유의적인 차이는 보이지 않았지만 전반적으로 핵성숙율이 향상된 것을 확인할 수 있었다. 따라서 개 난자의 체외성숙 시, 10 μg/ml의 LH와 FSH, 10 ng/ml의 EGF 그리고 0.57 mM의 cysteine을 첨가하는 것이 핵성숙율을 향상시키는 것으로 사료된다.

The present study was performed to determine the ability of canine oocytes to achieve nuclear maturation according to oocyte diameter and different culture environments. All of the collected oocytes were classified by grade 1 to 3 and by their diameters such as <100㎛, <100㎛ to <110㎛, <110㎛ to <120㎛, >120㎛. Oocytes were cultured in culture medium supplemented with 10%FBS, 0.4%BSA,10% porcine follicular fluid (pFF), 10% canine serum (CS), or 10% canine estrus serum (CES). The mean number of oocytes recovered from estrus status ovaries was significantly higher than that of anestrus status ovaries (p<0.01). The maturation rate of grade 1 oocytes (>120㎛) was significantly higher than that of the other groups (p<0.05). Nuclear maturation to MI to MII in diameter of >110㎛ groups was significantly higher than that in <100㎛ group (p<0.05). The oocytes cultured in 10% FBS­supplemented group were significantly higher rate of GVBD compared to the other supplemented groups (p<0.05), and oocytes maturation to MI to MII in 10% FBS-, 0.4% BSA-, and 10% pFF-supplemented groups were significantly higher than those in 10% CS-supplemented group (p<0.05). Based on these results, the estrus status and the size of oocyte affect positively to improve nuclear maturation of canine immature oocytes in vitro. Among several protein sources, porcine follicular fluid was the most effective supplementation to culture medium to achieve higher in vitro maturation rate.