Objective: To observe the effects of cumulus cells on in vitro fertilization.
Study design: Oocytes were retrieved from 47 patients (> 10/patient) who underwent short-term insemination from August 2009 to June 2010. The oocytes from each patient were divided into a cumulus cell-free group (cumulus cells were removed from the incubation medium 4 hours after coincubation of male and female gametes) with 389 oocytes and a cumulus cell group (cumulus cells were retained with the gametes until fertilization was evaluated 16-18 hours after co-incubation) with 402 oocytes.
Results: Polyspermic fertilization was 0.96 +/- 1.14 in the cumulus cell-free group and 0.47 +/- 0.72 in the cumulus cell group with p < 0.05. There were no significant differences in normal fertilization (5.96 ğ 1.73 vs. 6.55 +/- 3.72), 1PN fertilization (0.06 +/- 0.25 vs. 0.09 +/- 0.28), fertilization failure (1.34 +/- 1.17 vs. 1.45 +/- 1.84), cleavage (6.06 +/- 2.04 vs. 6.51 +/- 3.94), high-quality embryo (3.94 +/- 1.79 vs. 4.74 +/- 3.45) and usable embryo (5.06 +/- 1.86 vs. 5.68 +/- 3.98) between cumulus cell-free group and cumulus cell group, all with p > 0.05.
Conclusion: In our study short-term insemination (4 hours) causes a statistical increase in polyspermic fertilization. In order to ensure correct oocyte fertilization and reduction of polyspermic fertilization, it is better to retain the cumulus cells for 16-18 hours.