We have extensively characterized OME previously in terms of their histological markers and ultrastructure and so analysis was not performed in this study.27,31 MDM-OME displayed proliferating (ki67+) keratinocytes in the basal layer of the epithelium (Fig. 2C) that was also highly immunoreactive to the pan-cytokeratin antibody AE1/3 confirming the presence of differentiating keratinocytes throughout the epithelium (Fig. 2D). Here, MKI67 is linked to otitis media with effusion.