The Effect of Preincubation Time and Myo-Inositol Supplementation on the Quality of Mouse Mii Oocytes

Background: it is demonstrated that optimal preincubation time improves oocyte quality, fertilization potential and developmental rate. this study aimed to evaluate the effect of preincubation time in the simple and myo-inositol supplemented medium on the oocyte quality regarding oxidative stress and mitochondrial alteration. methods: cumulus oocyte complexes (cocs) retrieved from superovulated nmri mice were divided in groups of 0, 4 and 8 hr preincubation time in the simple and 20 mmol/l myo-inositol supplemented media. intracellular reactive oxygen species (h2o2), glutathione (gsh), mitochondrial membrane potential (mmp), atp content, and mitochondrial amount were measured and analyzed in experimental groups. one-way anova and kruskal-wallis were respectively used for parametric and nonparametric variables. statistical significance was defined as p<0.05. results: in comparison to control group, variables including ros, gsh, mitochondrial amount, fertilization and developmental rates were significantly changed after 4 hr of preincubation in the simple medium, while mmp decreased following 8 hr of preincubation in the simple medium (p˂0.001). preincubation of oocytes up to 8 hr in the simple medium could not decrease atp content. for both 4 and 8 hr preincubation times, myo-inositole could decrease h2o2 and increase gsh and mmp levels and consequently could improve fertilization rate compared to oocytes preincubated in the simple culture. conclusion: it seems that 4 hr or more preincubation time can decrease the oocyte quality and lead to reduced oocyte fertilization and developmental potential. howevere, myo-inositol may prevent oocyte quality reduction and improve fertilization potential in comparision to the equivalent simple groups.