Fig. 6.

Compensatory β-cell mass expansion began during the 1st wk of HFD. A–C: β-cell mass had begun to increase after only 7 days of HFD (n = 12; A). This increase was not due to increased pancreas weight (n = 12; B) but instead to an increase in percent pancreatic area made up of islets (n = 12; C). D: size of individual β-cells was not altered by HFD treatment (n = 4). E: analysis of size distribution of pancreatic islets revealed no increase in the number of very small islets (n = 8). F: high-fat feeding increased the proliferation rate to a similar degree in islets of all sizes (n = 4). These data are from mice treated with BrdU in the drinking water on days 3–7. Data are expressed as means ± SE; P values were calculated by Student's t-test (A–D) or two-way ANOVA with Bonferroni correction for multiple comparisons (E: P < 0.0001 for islet size, P = ns for diet; F: P < 0.0001 for diet, P = ns for islet size). **P < 0.01.