Scheme of MII oocyte collection and expression analysis of Tert transcripts and protein. (A) Diagram showing the study design for collecting fresh oocyte retrieved from young or reproductively-aged females, and oocytes aged in vivo or in vitro after ovulation (OPU: oocyte pick up). (B) Q-PCR analysis of Tert in MII oocytes. Gapdh was used as an internal standard for gene expression (n: number of replicated experiments). The error bars show mean ± SEM. *P < 0.05; ****P < 0.0001. (C) Immunocytochemical analysis of TERT expression (yellow). Nuclei were stained with DAPI (blue). Fresh oocytes from reproductively-aged females exhibited weaker TERT signal intensity than fresh oocytes from young females. (D) Quantification of relative TERT fluorescence intensities shown in 1C (N: total number of oocytes). The error bars show mean ± SEM. ****P < 0.0001.