The expression in the Dicer1-hypomorphic mice was normalized to that in the wild-type mice.

The islets mass was measured in wild-type (blue bar) and Dicer1-hypomorphic mice (pink bar). The numbers of islets were examined in wild-type (n = 6) and Dicer1-hypomorphic (n = 6) mice, with six sections from each animal. The graph shows the percentage of islets in each size category.

Data are expressed relative (n-fold) to the wild-type pancreas and correspond to the means and standard errors for three independent experiments performed in triplicate. *, P<0.05. wild-type n = 9, Dicer1-hypomorphic mice n = 9.

Male wild-type (+/+) and Dicer1-hypomorphic (−/−) mice were measured to determine the change in body weight from 10 to 80 days of age. *, P<0.05. n = 8–10 per group.

Dicer1-hypomorphic mice show normal insulin (brown) and glucagon (blue) staining at E15.5 and P1. C: Histological abnormalities found in the pancreas of 4-week-old Dicer1-hypomorphic mice. (I) The endocrinal distribution was slightly irregular. The dotted line indicates the abnormal region of the islet. (II) Multi-nucleated cells were observed. The dotted line indicates multi-nucleated cells, which were also found in the pancreas of adult Dicer1-hypomorphic mice.

A: Glucose tolerance test. Fasted 8-week-old mice received an intraperitoneal injection of glucose (2 mg/g body weight). B: Insulin concentration. Plasma insulin was measured before and after the intraperitoneal glucose injection. C: Growth hormone concentration. Plasma growth hormone concentrations were measured in wild-type and Dicer1-hypomorphic mice. A, B: Values are expressed as the means±S.D. (n = 20 per group). C: Values are expressed as the means±S.D. (n = 10 per group).*, P<0.05.

A, B: Hematoxylin-eosin (H & E)-stained islets of the pancreas from an 8-week-old wild-type (+/+) mouse and Dicer1-hypomorphic (−/−) mice (*400). A: Arrows indicate an irregular distribution of islet cells. B: Arrowheads indicate that the boundary of islets and ducts was not clearly defined in the pancreas of Dicer1-hypomorphic mice. C: Immunohistochemistry of duct cells of Dicer1-hypomorphic mice. (I) Insulin (green) and glucagon (red) double-expressing cells were detected in the duct. (II) Insulin-positive cells (brown) and glucagon-positive cells (blue) were observed in the duct. (III) Comparison of the number of epithelial cells stained with both insulin and glucagon, only insulin, and only glucagon in wild-type and Dicer1-hypomorphic mice. These numbers were averaged from 6 animals, with six sections from each animal. **, P<0.01. (IV) Comparison of the proportion of ducts containing epithelial cells stained with Pdx1 in wild-type and Dicer1-hypomorphic mice. Arrowheads indicate the Pdx1-positive cells. *, P<0.01. (V) Abnormal staining of Ki67 was observed in the pancreas of Dicer1-hypomorphic mice. D: (I) H & E-stained multinuclear atypical cells in the pancreas of Dicer1-hypomorphic mice. The black dotted line indicates atypical multinuclear cells. (II) Comparison of the number of multi-nucleated cells in wild-type and Dicer1-hypomorphic mice. These numbers were averaged from 6 animals, with six sections from each animal. **, P<0.01. E: Immunohistochemistry of multinuclear atypical cells of adjacent sections of the pancreas of Dicer1-hypomorphic mice using anti-insulin (I) and anti-glucagon (II) antibodies. F: H & E-stained acinar cells. The rectangular areas outlined in the upper panels are magnified in the lower panels. An abnormal structure of exocrine cells was observed in the pancreas of Dicer1-hypomorphic mice.