Background and purpose: Mitomycin C (MMC) is used as an antiproliferative agent for feeder cells in cell culture. It may induce destructive effects on these cells and eventually on oocytes maturation. This study was conducted to investigate the effect of MMC and co-culturing with fibroblast and cumulus cells on in vitro maturation (IVM) of mouse immature oocytes.

Materials and methods: In this experimental study, germinal vesicle oocytes (GV) obtained from NMRI mature female mice were cultured in αMEM supplemented by FSH, hCG, fetal bovine serum (FBS), penicillin and streptomycin, at 37 °C and 5% CO2 in following groups: a control group and four experimental groups; 1– co-cultured with cumulus cells, 2 – co-cultured with mouse embryonic fibroblast (MEF) cells, 3 - co-cultured with cumulus cells treated with MMC, and 4 - co-cultured with MEF treated with MMC. After 24 hours, number of GV, GVBD, MII and degenerated oocytes were determined using invert microscope. Data were analyzed using ANOVA with Tukey test.

Results: The percentages of GV (24±2.75) and MII (51±2.28) oocytes in control group were significantly higher (8±2.25, 10±2.29, 10±2.28, 11±1.19) and lower (64±2.34, 63±2.62, 62±2.86, 62±2.47) than those in all experimental groups, respectively. Nevertheless, no significant difference was observed between experimental groups.

Conclusion: Co-culturing with fibroblast and cumulus cells promoted in vitro maturation of immature oocytes. There was no significant difference among experimental groups, therefore, removal of monolayer inactivation step by MMC from such protocols can be proposed.