Helium-neon (He-Ne) laser irradiation increases the incidence of unreducedbovine oocytes during the first meiotic division in vitro

Low power He-Ne laser irradiation was applied to immature bovine oocytes to investigate the incidence of unreduced oocytes (diploid oocytes) during th e first meiotic division in vitro. Immature bovine oocytes from cows killed at a slaughterhouse were irradiated with He-Ne laser irradiation at 0.05 a nd 0.25 J/cm(2) exposures. An oocyte group was left untreated serving as th e control group. All oocytes were matured in TCM-199 medium supplemented wi th 10% fetal calf serum (FCS). Unreduced oocyte percentages obtained in the irradiated oocytes group were significantly higher (p<0.01 and p<0.001, re spectively) than those of the control group. Furthermore, the laser-treated oocytes showed a degeneration rate significantly higher (p<0.01 and p<0.00 1, respectively) than those observed in the control group. It is concluded that the application of He-Ne laser irradiation at 0.05 and 0.25 J/cm(2) ex posures increased the incidence of unreduced oocytes and the percentage of degenerated oocytes during the in vitro meiosis process of immature bovine oocytes.