Effect of Time of in vitro Maturation of Bovine Oocytes on the Meiotic Progression. Technical Note

The aim of this study was to investigate the effect of the duration of in vitro maturation of bovine oocytes on meiotic progression. To do this cumulus oocyte complexes (COC) were obtained from ovaries of female animals slaughtered, COC were set to mature in TCM 199 supplemented with 10 mu g/mL of FSH (Folltropin-V (R)), 1 mu g/mL 17 beta estradiol, 50 ng/mL of epidermal growth factor and 10% fetal bovine serum, at 38.5 degrees C in 5% CO2 in humidity saturated air during 23 to 27 hours. COC were stripped from cumulus cells and fixed in a solution of methanol: acetic acid (3:1) and stained with aceto-orcein (1.1%) to evaluate meiotic progression. After 23 hours, the rate of maturation reached 59.71%, a value which rose to 83% at 26 hours and then declined to 56.25% at 27h. The proportion of degenerated oocytes after culture in vitro also increased with increased duration of maturation time from 0% at 23 hours, and up to 10.41% at 27 hours. This study found that development competence of bovine oocytes is affected by the duration of maturation in vitro.