Figure 9 Native Barrett's oesophagus (BE) biopsy specimens have immature deep glands, which resemble the retinoic‐acid‐induced changes. Biopsy specimens have been stained with H&E, and viewed with the light microscope or with TO‐PRO‐3 DNA stain (blue), cytokeratin (CK)8/18 (green), vimentin (red) and dual labelling. The mature glands (arrowheads) in this representative biopsy specimen have nuclei, which are configured in a clear glandular arrangement and stain with CK8/18 with no expression of vimentin. In contrast, there are more immature areas (arrows) in which the nuclei are more loosely palisaded with weak expression of CK8/18 and speckled vimentin in the same areas.