CONICET | Buscador de Institutos y Recursos Humanos

After ovulation, mature oocytes only have a short optimal time span for fertilization to take place. If not fertilized in time, these oocytes will undergo a time-dependent quality degradation process called postovulatory aging. In assisted reproduction technologies (ART), oocytes are inevitably subjected to postovulatory aging. This leads to poor embryonic development after fertilization, increases abortion rates and decreases offspring longevity. Although quite significant technical progress has been made to improve ART technologies, poor oocyte quality is the key factor closely associated with ART failure. Understanding the underlying mechanisms in the oocyte aging process and finding chemicals that can reverse postovulatory aging are two of the most important research topics today. In previous work we demonstrated that cortical granules density decreases in in vitro aged mouse oocytes. Dithiothreitol (DTT) is a dithiol with two end sulfhydryl groups that prevents membrane fusion during the first cell cycles in sea urchin. Therefore, we hypothesized that DTT might prevent premature secretion of cortical granules in in vitro aged mouse oocytes. Mature oocytes were obtained from hormonally stimulated CF-1 female mice. For achieving in vitro aging, oocytes were collected 16 h post hCG (control oocytes) and in vitro cultured by 4 or 8 h (aged oocytes). When in vitro aging was performed in the presence of different DTT concentrations, the quantification of cortical granules density showed that in vitro aged and control oocytes had similar cortical granules density. Hence, these results suggest that the addition of DTT to the culture medium might be useful to avoid the premature secretion of cortical granules, improving the ART rate success.