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In several species, the developmental competence of the oocyte is acquired progressively during late follicular growth, after the acquisition of the competence to resume and complete meiosis. In the pig, full meiotic competence of the oocyte is reached in ovarian follicles with a diameter of 3mm or more. However, there is no information about developmental competence acquisition. We analyzed the ability of oocytes from three follicular size classes to resume and complete meiosis, to be fertilized, and to develop in vitro to the blastocyst stage. A total of 941 follicles were dissected from slaughterhouse gilt ovaries and classified as small (<3mm, n=330), medium (3–5mm, n=373), or large (>5mm, n=238). The cumulus–oocyte complexes recovered from these follicles were submitted to in vitro maturation for 44h in TCM199 supplemented with 10ng/ml EGF, 400ng/ml pFSH and 570μM cysteamine; in vitro fertilized for …