Sections from paraffin-embedded tissue blocks of normal human ileum and colon were stained with polyclonal rabbit anti-human antisera to CSF1R and a horseradish peroxidase-conjugated goat anti-rabbit secondary antibody with diaminobenzamide used as chromagen. A. Superficial epithelium of the terminal ileum with cytoplasmic staining of the terminal web and lateral junctions of the epithelial cells (green arrow). B. Staining of the superficial epithelium of the colon. C. Staining of the superficial epithelium of the ileum with an epithelial cell being sloughed off into the lumen (green arrow). 100×.