Heterochronic parabiosis increased β-cell replication of old mice. A: Parabiosis was performed in young mice and old mice to create isochronic and heterochronic groups. After 3 weeks, mice were
killed and proliferation was measured using Ki67. Student t test demonstrated a significant increase in replication between old isochronic mice and old heterochronic mice (**P < 0.01, whereas ANOVA analysis of the experiment yielded P < 0.001). Post hoc Tukey honestly significant difference test also showed a significant difference between old isochronic
mice and heterochronic mice (*P < 0.005). B: Representative images of the islets from four different groups of parabiosed mice stained for insulin (green), DNA (red),
and Ki67 (blue) (N ≥ 4). Het, heterochronic; Iso, isochronic; NS, not significant; Yhet, young heterochronic; Yiso, young isochronic.