Iron transport from duodenal epithelial cells into the circulation is impaired in cre/+ mice. (A) Graphical presentation of ⁵⁵Fe administration via gavage in control (+/+) and cre/+ mice aged between 9 and 15 weeks old. One hour after administration, indicated tissues were collected and analyzed. (B) Quantification of radioactivity of ⁵⁵Fe after 1 hour absorption in the duodenum (∗∗P = .008), liver (P = .09), spleen (P = .59), serum (P = .23), and BM (∗∗P = .002). (C) Pie chart illustrating ⁵⁵Fe distribution in the tissues in percentage. Fe retention is expressed as a percentage of the total ⁵⁵Fe measured in all the collected samples. (D) Representative image of ferric iron Prussian blue staining on duodenum FFPE sections obtained from +/+ and cre/+ mice, counterstained with nuclear fast red. Quantification of the blue-stained area in the duodenal LP (∗P < .05). Scale bar, 50 μm. (E) Total iron concentration was measured using AAS in the upper intestine including the duodenum of 8- to 12-week-old control (+/+) and cre/+ mice. (∗P < .05). (F) Representative image of immunofluorescent staining for ferritin (iron storage protein) and F4/80 (macrophage marker) on mouse duodenum cryosections obtained from +/+ and cre/+ mice. Scale bar, 50 μm. (G) Graphical presentation of IV iron dextran (Fe-dext) treatment of +/+ and cre/+ mice aged between 9 and 15 weeks old, as indicated. Control (+/+) mice were treated with sterile 1× PBS. After 4 weeks of treatment, tissues were collected and analyzed. (H) Representative image showing the BM isolated from controls (+/+) and cre/+ in mice treated with Fe-dext. (I) Tf saturation, unsaturated iron binding capacity, and TIBC of transferrin in serum were determined in mice treated IV with Fe-dext, and compared with controls (+/+) treated with 1× PBS (∗P < .05; ∗∗∗P < .001).