Evidence of intraovarian follicular dominance effects during controlled ovarian stimulation in a sheep model

ObjectiveTo evaluate intraovarian dominance effects in a sheep model and to determine whether local factors, independent of FSH-mediated pathways, are capable of interfering with the final development of subordinate follicles.DesignObservational, model study.SettingPublic research unit.Animal(s)Three hundred sixty-four adult Manchega ewes.Intervention(s)Synchronization of estrous cycle with intravaginal progestogens and ovarian stimulation with FSH; ovarian ultrasonography, laparoscopies, and embryo recoveries.Main Outcome Measure(s)Determination of morphological characteristics and developmental competence of ovarian follicles.Result(s)The presence of a dominant follicle affects number and viability of embryos from the ipsilateral ovary in females that are treated with high FSH doses; this effect, modulated by season and phase of the estrous cycle, highlights the role of LH in follicular dominance.Conclusion(s)The current study confirms, in a sheep model, the existence of local effects from dominant follicles over neighboring follicles, by direct action and independently from systemic pathways through FSH modulation.