Figure 2. Telomere dysfunction and DNA damage in aged oocytes and embryos. (A) Relative telomere length in oocytes and two-cell embryos is expressed as a T/S ratio determined by quantitative RT-PCR analysis. Data are expressed as mean percentage ± SD of three independent experiments (oocytes: n=114 young, n=106 old; embryos: n=85 young, n=86 old). (B) Representative images of oocytes/two-cell embryos stained with antibodies against TRF1 (red) and γH2AX (green), and co-stained with Hoechst 33342 for chromosomes (blue). PB, polar body. Scale bars, 25 µm. (C–D) Quantification of DNA damage-induced foci (TIFs) from (B). TIFs were detected by co-localization of TRF1 and γ-H2AX, and cells with at least 3 TIFs were scored. Data represent averages of 3–10 fields. Error bars indicate SD (oocytes: n=24 young, n=26 old; embryos: n=35 young, n=38 old). Statistical analyses were performed with Student’s t-test. *P <0.05, **P <0.01.