PPL and Infertility: Among the top six proteins that showed a significant increase in infertile IOF, the expression of Mucin 5AC (MUC5AC) was significantly increased in infertile compared to fertile organoid cells (P<0.05), while no significant differences were identified in the expression of Lymphocyte cytosolic protein 1 (LCP1), RNASE1, Cathepsin H (CTSH), BPI fold containing family b member 1 (BPIFB1) and Periplakin (PPL) between groups (Figure 6C).