FGF2, LIF, and IGF1 enhance mitochondrial function and developmental competence in porcine oocytes from small antral follicles

Abstract Oocyte developmental competence is strongly influenced by follicle size, with oocytes from small follicles exhibiting reduced capacity for maturation and embryo development. Optimising in vitro maturation (IVM) conditions may help overcome these intrinsic limitations. Porcine oocytes derived from small and large antral follicles were matured in vitro for 44 h in a TCM199-based IVM medium either without supplementation (control) or supplemented with FGF2, LIF, and IGF1 (FLI). Developmental competence was assessed by determining the success of cleavage after parthenogenetic activation. Intracellular redox status, mitochondrial distribution, and expression of genes related to mitochondrial function, antioxidant defence were evaluated using fluorescence-based assays and molecular analyses. Oocytes from small follicles showed reduced cleavage and blastocyst rates compared with large follicle oocytes under standard conditions in control medium. FLI supplementation significantly improved developmental outcomes in both groups. Small follicle oocytes displayed a distinct redox profile and increased susceptibility to oxidative stress during standard maturation, whereas FLI improved redox homeostasis, mitochondrial organisation, and gene expression associated with oocyte competence. FLI supplementation enhances oocyte quality by improving redox regulation and cytoplasmic maturation, partially overcoming the intrinsic limitations of small follicle–derived oocytes. These findings emphasise the importance of optimised culture systems to improve oocyte competence and embryo production.