FIGURE 1.

Systemic treatment with diphtheria toxin (DT) lesions hair cells in the utricles of Pou4f3–huDTR (human form of the diphtheria toxin receptor) transgenic mice. Knock-in mice in which one copy of the gene for Pou4f3 was replaced with the gene for huDTR received a single 25 ng/gm injection of DT. After 7 days, mice were perfused and utricles were immunolabeled for myosin VI (red, hair cells) and also stained with phalloidin (green). A partial loss of hair cells was observed in the utricles of Pou4f3–huDTR mice (A), when compared with littermates that did not possess the Pou4f3–huDTR transgene, but were also treated with DT (B). Scale bar = 20 μm.