Figure 5. Effect of SIRT1 up-regulation induced by 17β-E2 on cell autophagy in hFOB1.19 osteoblasts. TEM images showed more double-membrane vacuoles (autophagosomes) in cells treated with 17β-E2 + SRT1720 compared with those in the control group and 17β-E2 + EX527 group. The histogram showed the number of autophagosomes in different groups as indicated. The autophagic vacuoles are indicated with black arrows. Black bar: 1 μm. * P < 0.05 vs. the control group was considered significant.