Effects of Ovary Status and In Vitro Maturation Condition on the Developmental Competence of Canine Oocytes

Abstract

In canine, oocytes are ovulated at the GV (germinal vesicle) stage and they have to fulfill maturation phase before reaching metaphase ΙΙ stage. The efficiency of in vitro maturation is still very low. Therefore, the aim of this study was to investigate the effect of in vitro maturation on nuclear changes of immature canine oocytes recovered from different reproductive stages ovaries and different culture conditions. The oocytes were cultured in TCM-199 with supplement at 5% CO2 and 38.5℃ for 72 h. The nuclear maturation of canine oocytes was evaluated with Hoechst 33342 stain under fluorescence microscope (Fig. 1). The results of this study detected differences in in vitro maturation rate between oocytes recovered from follicle status and non-follicle status ovaries. However, these differences were not significant as indicated in Table 1 and Fig. 2. In regard to the effect of culture condition with supplements, we did not found significant differences compared with control group (Table 2, Table 3). One of the reasons for this data could be the conditions that ovaries were exposed during slaughtering process or the long distant transportation of the ovaries. Although these data have not shown clearly significant differences results compared with control,furthermore the different reproductive status ovaries was beneficial for maturation of oocytes in vitro and can be a basic part of knowledge to improve in vitro maturation of canine oocytes.