Abstract

Mitochondrial distribution and activity are closely associated with cytoplasmic maturation and developmental competence in mammalian oocytes; however, limited information is available regarding these processes in Vicugna pacos. This study aimed to characterize mitochondrial activity, aggregation, and distribution patterns in immature and in vitro mature Vicugna pacos oocytes. Mitochondrial fluorescence intensity ranged from 21.2 to 126 units, with mean values decreasing from grade I to IV. No significant differences were observed between immature (66.8 ± 22.7) and mature (59.2 ± 23.5) oocytes. Three distinct distribution patterns were identified: homogeneous non-peripheral (HoNP), heterogeneous peripheral (HeP), and heterogeneous non-peripheral (HeNP), with HeNP oocytes exhibiting the highest activity. During maturation, fluorescence intensity increased in HeNP and HeP but decreased in HoNP, suggesting distinct mitochondrial responses. Aggregation shifted from smooth in immature oocytes to granular in mature ones, and these two traits—HeNP distribution and granular aggregation—were consistently associated with higher mitochondrial activity. Overall, 78% of oocytes showed aggregation. These results demonstrate that mitochondrial remodeling accompanies oocyte maturation and that aggregation and distribution patterns may serve as biomarkers of oocyte quality. Further studies linking these features with fertilization and embryo development are needed to validate their predictive role in assisted reproduction of alpacas.

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