Pdx1 inactivation restricted to the intestinal epithelium alters iron metabolism in mature mice. Average red blood cell size (mean corpuscular volume, MCV) (A) and hemoglobin amount per red blood cell (mean corpuscular hemoglobin, MCH) (B) were measured in the blood samples from 3- and 6-mo-old Pdx1flox/flox;VilCre (n = 8) and littermate control Pdx1flox/flox mice (n = 3). *P < 0.005. The presence of nonheme iron (blue) in the mucosa was visualized by Perls Prussian blue stain of duodenal sections from 6-mo-old littermate control Pdx1flox/flox (C, E, and F) and Pdx1flox/flox;VilCre (D) mice. Diffuse blue nonheme iron staining was observed in the villous epithelium (C and E), whereas concentrated iron staining was mainly found in the lamina propria (F). C and D: representative views taken at comparable location in the duodenum of littermate control and Pdx1flox/flox;VilCre mice. E and F: higher magnification of control duodenal mucosa showing the presence of nonheme iron in the epithelial cells and lamina propria. Lu, lumen; Br, Brunner's glands.