Treatment With Roscovitine And Butyrolactone I Prior Toin Vitromaturation Alters Blastocyst Production

This study evaluated the effects of oocyte meiosis inhibitors roscovitine (ROS) and butyrolactone I (BL-I) onin vitroproduction of bovine embryos. Bovine oocytes were maintained in prein vitromaturation (pre-IVM) with 25 mu M ROS or 100 mu M BL-I for 24 h to delay meiosis and for 24 h inin vitromaturation (IVM). Following this treatment, the nuclear maturation index was evaluated. All embryos degenerated following this procedure. In the second set of experiments, oocytes were maintained for 6 or 12 h in pre-IVM with the following three treatments: ROS (25 mu M or 12.5 mu M), BL-I (100 mu M or 50 mu M) or a combination of both drugs (6.25 mu M ROS and 12.5 mu M BL-I). Oocytes were cultivated for 18 or 12 h in IVM. When a meiosis-inducing agent was used during pre-IVM for 24 h, more degenerated oocytes were observed at the end of the IVM period. This effect decreased when the meiotic blocking period was reduced to 6 or 12 h. No significant differences were observed in the blastocyst production rate of oocytes in pre-IVM for 6 h with ROS, BL-I, or ROS + BL-I compared with that of the control group (P> 0.05). However, inhibition of oocytes for 12 h resulted in decreased embryo production compared with that in the controls (P< 0.05). There was no difference in the post-vitrification embryo re-expansion rate between the study groups, showing that the meiotic inhibition for 6 or 12 h did not alter the embryo cryopreservation process.