Figure 3. Redistribution of cochlear macrophages following ototoxic injury.

The hyaline cell regions of undamaged cochleae contained numerous macrophages (A, green). After ototoxic injury, increased numbers of macrophages were observed within the sensory region (B). Macrophage numbers in the sensory and hyaline regions were quantified using the scheme shown in (C). Data from undamaged cochleae indicated that the hyaline cell region contained more macrophages than did the adjacent sensory region (D, left, p<0.001). After injury, however, macrophages in the sensory region outnumbered those in the hyaline region (D, right, p<0.001). This apparent redistribution suggests that resting macrophages migrate into the sensory region in response to hair cell injury, as schematized in (E). Scale bar = 30 µm.