In situ hybridization analysis of TfR2, Nramp1, FPN1, and HFE. In situ hybridization analysis of TfR2 (panel A), Nramp1 (panel B), FPN1 (panel C), and HFE (panel D) genes in rat liver tissue. For each gene, the images from the analysis of both antisense and sense probes are shown. The former represent the gene-specific probe, while the latter are used as negative controls. Owing to the variations in expression levels of the examined genes, the incubation times for the last step of the procedure (BM purple color development) varied so that we could obtain optimal images. The incubation times for TfR2, Nramp1, and FPN1 were 48 hours. The incubation time for HFE was 72 hours. All images were taken under × 100 original magnification.