Fig. 1

Establishment of surgical procedures for the externalization and removal of the cecal epithelium. A Gross view of the mouse cecum. B A small incision was made at the distal end of the cecum. C The luminal contents of the cecum were pushed out of the incision. D After the removal of the luminal contents, the cecal wall was inverted from the incision to expose the luminal epithelium. E Gross view of the externalized luminal surface of the cecum. F The cecal surface was stained with Fast Green to visualize the epithelial layer. G A magnified view of the cecal surface stained with Fast Green. Individual crypts were identifiable as small white spots, which were efficiently removed by mechanical brushing. H Gross view of the epithelium-removed surface of the cecum. I, J Confirmation of the absence of epithelial cells within the crypts via Nuclear Green staining. Each black hole represents a single crypt devoid of epithelial cells. J Magnified view of the cecum surface before and after epithelial removal. K Staining of mucus granules with Rhodamine-UEA-I (red) present in the differentiated epithelial cells of the cecum. Nuclei were stained with Hoechst33342 (blue). Comparison of sections from the normal (left) and epithelium-removed (right) cecum confirmed the successful removal of the differentiated cells