Effect of Ovary Transport Temperature on Survivability and Maturation Rate of Canine Oocytes

This study examined the viability of canine oocytes following storage at 4 or $38{\circ}C$ for 5 hrs. The ovaries were collected from domestic dog following ovariohysterectomy at a local veterinary clinics and transported to laboratory In two different transport temperature at 4 or $38{\circ}C$ within 5 hrs. The cumulus oocyte complexes (COCs) were recovered after slicing with blade. In Exp. 1, the oocytes collected were matured in DMEM supplemented with l0% FBS, 0.6 mM/mlcysteine, 0.2 mM Pyruvic acid, 20 ng/ml $E_2$ and 1 $\mu g/ml$ rbST at humidified atmosphere containing 5% $CO_2 38{\circ}C$ for 24 or 48 hrs to analysis of survivability. In Exp 2, to assess nuclear development at 38{\circ}C$ group, the oocytes were matured in maturation medium for 24, 48 or 96 hrs. Survivability was judged by a morphological appearance and PI staining. Survivability rates were analyzed by General Linear Models procedure in SAS. The survival rates at 4{\circ}C$ ovary transport group showed significantly lower than at 38{\circ}C$ group (0 vs 72.9% in 48 hrs and 13.2 vs 77 8% in 24 hrs; P<0.05). The nuclear development of oocytes to MI to MII stages at 24, 48 and 96 hrs was 8.3% (6/72), 8.9% (9/101), and 9.5% (8/84). These results showed that the canine oocytes were remarkably sensitive to a low temperature and did not increase nuclear development rate depend on maturation time to 96 hrs.