Figure 4.

Mitotic HC generation through the overexpression of Atoh1 (Atoh1-OE). A, In control mice, there are no ectopic HC or EdU⁺Myo7a⁺ HCs in the cochleae. B, Overexpression of Atoh1 in Sox2⁺ SCs resulted in numerous ectopic HCs in the GER, whereas few EdU⁺Myo7a⁺ HCs were identified in the cochlea. C, Only a limited number of proliferative SCs differentiated into HCs in the β-cat-OE/Atoh1-OE mice. D, E, In the β-cat-OE/Notch1-KO/Atoh1-OE mice, numerous EdU⁺Myo7a⁺ HCs were detected in both the sensory region and GER. E, Quantification and comparison of the number of EdU⁺Myo7a⁺ HCs in both the sensory region and GER among different groups. F, Cross-section of the cochleae from β-cat-KO/Notch1-KO/Atoh1-OE mice. G, EdU⁺Myo7a⁺ HCs in the GER at high magnification. Arrows indicate the EdU⁺Myo7a⁺ HCs. Data in E are presented as mean ± SEM. **p < 0.01. The dotted lines in A2 show the counting limits of HCs in the sensory region and GER. Scale bar, 50 μm.