Proteomic changes during the final steps of human oocyte maturation. DAPs were identified during the meiotic maturation of human oocytes. Volcano plots show DAPs identified by plexDIA between MII and GV oocytes from the (a) Young and (b) AMA groups. Protein name is indicated for statistically significant DAPs (P.adj ≤ 0.05, Wilcoxon test, ǀfold changeǀ> 1.5). Dot colour indicates protein abundance in MII oocytes compared to GV: purple (more abundant), green (less abundant), and grey (stable levels). (c) Heatmap showing the Log₂ levels of DAPs for all oocyte groups, red (high levels), blue (low levels). (d) Ontology terms representing the pathways that statistically differ between GV and MII oocytes in Young and AMA groups (Wilcoxon test, P.adj ≤ 0.05). Dot size reflects the ratio of identified proteins that change during GV to MII transition to the total proteins within the respective pathway. Dot color represents the P. adjusted value (Wilcoxon test), red (high values), blue (low values). AMA, advanced maternal age; DAPs, differentially abundant proteins; GV, germinal vesicle; MII, metaphase II; Young, 18–30 years; AMA, 37–43 years.