Homo sapiens glandular columnar epithelium anal canal epithelium transitional glandular epithelium of anorectum glandular epithelium of the anal transition zone anorectum transitional glandular epithelium UBERON:8410005 glandular epithelium of anal transition zone Glandular epithelium of the anal transition zone. The anal transition zone is defined loosely as the tissue interposed between the uninterrupted squamous epithelium of the anoderm and the uninterrupted mucosal epithelium of the anal canal in the anorectum. Paola Roncaglia