Figure 1

Immunolabeling showing the phenotypic expression of lysozyme in the E-tube. The schematic illustration showing right tympanic bulla and E-tube of a mouse (A). ME: middle ear, ET: Eustachian tube, NP: nasopharynx, TM: tympanic membrane, PO: pharyngeal orifice, TO: tympanic orifice, C: tubal cartilage, TL: E-tube lumen. Cross-sections at level b, c and d of both wild type and lysozyme M^-/- mice are shown in B, C and D. Lysozyme is labeled in both the submucosal gland (SG) and the E-tube epithelium (arrow heads) of wild type mice while it is labeled predominantly in the submucosal gland (SG) of lysozyme M^-/- mice. This indicates that lysozyme P of lysozyme M^-/- mice is predominantly expressed in the submucosal gland, not in the tubal epithelium, considering that the polyclonal antibody recognizes both lysozyme M and lysozyme P. The secretion in the tubal lumen (arrow) is also immunolabeled with lysozyme in wild type mice, but not in lysozyme M^-/- mice. All sections were immunolabeled with anti-human lysozyme antibody (1:1,000) and counterstained with hematoxylin. For each pair of images the left-hand panel displays sections from wild type mice and the right-hand displays sections from lysozyme M^-/-mice. TC: tubal cartilage, TL: E-tube lumen. SG: submucosal gland. Original magnification: × 100.