Increased BrdUrd labeling of β-cell nuclei in WT islet grafts transplanted into DH and ob/ob mice and endogenous pancreas of insulin-resistant mice. (a) Cross sections of WT islet grafts dissected from WT (Left), DH (Right Upper), and ob/ob (Right Lower) recipients were stained for BrdUrd and mixture antibody as described under Methods. BrdUrd positive nuclei are stained black (arrows), and non-β-cells are stained brown-black. Representative sections are shown. (b) Mitotic index of β-cells in islet grafts: *, P < 0.0001, WT vs. DH, n = 12–13; *, P < 0.0001, WT vs. ob/ob, n = 6–13. All values are means ± SEM. (c) Mitotic index of β-cells in endogenous pancreas: *, P < 0.05 WT vs. DH or ob/ob, n = 3–4. All values are means ± SEM.