Hematoxylin and eosin staining of the middle ear in adult mice indicated otitis media.

<p>Clear middle ear cavity (MEC) and thin mucoperiosteum in wild type mice (A,C). MECs of <i>Mcph1^tm1a</i>^/<i>tm1a</i> mice (B,D) were filled with exudate and lined with thickened mucoperiosteum. High magnification for mucoperiosteum of MEC framed in A and B (C,D). Inflammatory cells (E,F) in MECs. Scale bar, 200 µm (A,B), 20 µm (C–F).