Figure 10

Typical images of Tlr4 immunoreactivity of the sensory epithelium from cochleae collected 1 day after acoustic trauma. (A) Tlr4 immunoreactivity is present in inner hair cells and Hensen cells. Arrows indicate increased Tlr4 immunoreactivity in the Deiters cell region. (B) Image (A) is superimposed with propidium iodide staining to illustrate the nuclear morphology. Notice that Tlr4 fluorescence (marked by the arrows) is located in the Deiters cells adjacent to the areas of missing nuclear staining of outer hair cells, indicating that the increase in Tlr4 in Deiters cells is associated with sensory cell damage. (C) A typical image showing that outer hair cells exhibit only weak Tlr4 immunoreactivity. Notice that the image of inner hair cells in this figure is not shown because the inner hair cell image is out of the optical layer of the confocal image. (D) and (E) A typical example of the increase in Tlr4 immunoreactivity in a Deiters cell beneath a degenerated outer hair cell. The tissue was doubly stained with prestin (red fluorescence), an outer hair cell specific protein, to illustrate the bodies of outer hair cells (E). The arrow in (D) and (E) indicates an outer hair cell with a malformed cell body, an indication of ongoing degeneration. The Deiters cell beneath this degenerating outer hair cell displays increased Tlr4 immunoreactivity. (F) Comparison of the gray level of staining intensity between the Deiters cells beneath surviving outer hair cells and the Deiters cells beneath dying outer hair cells. The average of the fluorescence intensity in the Deiters cells beneath dying outer hair cells is significantly higher than the Deiters cells beneath the surviving outer hair cells (Student’s t-test, P <0.001). DC: Deiters cells; HC: Hensen cells; IHC: inner hair cells; OHC: outer hair cells.