Received November 26, 2005
Accepted November 29, 2005

The aim of our study was to evaluate the incidence of in vitro maturation of oocytes in a culture medium without hormonal supplementation, within 24 and 48 hours after retrieval. A total of 44 patients submitted to IVF that donated their immature oocytes for research were included in the study. All patients had the same superovulation protocol. Once the follicles reach the size of 17mm, 10.000IU of hCG was administered to induce maturation. Oocyte retrievalwas performed ~34hs later. The GV stage oocytes were placed in 20 μL droplets of hormone free culture media. After 24hours, oocytes were analyzed and those who presented polar body were considered mature. The remainders were placed in fresh droplets of the same culture media. After more 24 hours oocytes were reanalyzed. A total of 134GV stage oocytes were included in our study. After 24 hours, 57.5% of the oocytes were at metaphase II and after 48 hours 63.4% of all GV stageoocytes did reach metaphase II stage. The comparison between the two periods of time did not show statistical significance(p=0.16), demonstrating that the further 24 hours culture did not increase the maturation rate. Our study demonstrates that in vitro oocyte maturation in a hormone free culture media is a feasible procedure. Also, we did observe that extending the maturation time does not increase the maturation rate