Fig. 2

Immunohistological analysis of WT and Pou4f3DTR/+ mice after DT administration. A Immunohistochemistry of WT (Pou4f3+/+) and Pou4f3DTR/+ mouse organ of Corti at day 3 after DT administration. Green indicates Myo7a, red indicates Phalloidin, and blue indicates nuclear (DAPI) staining. Hair cells of WT mice are intact (a) for apical (b–e), middle (f), and basal turn (g), while those of Pou4f3DTR/+ mice, especially in the apical (h–l) and middle turn (m), lose their form. Scale bars represent 100 μm. B The graphs show numbers of Myo7a+ cells in the cochlear turns on day 3 after DT injection. The numbers in the apical and middle turn of Pou4f3DTR/+ mice are significantly lower than those of WT (n = 4), WT with DT (n = 5), and Pou4f3DTR/+ mice without DT (n = 5). In the Pou4f3DTR/+ with DT group (n = 6), the number of Myo7a+ cells in the apical turn is significantly higher than that in the basal turn. *P < 0.05. **P < 0.01 (one way ANOVA and Student’s t test). C Immunohistochemistry of Pou4f3DTR/+ mouse organ of Corti at day 7 (a–c), day 14 (d–f), and day 28 (g–i) after DT administration. Green indicates Myo7a, red indicates Phalloidin, and blue indicates nuclear (DAPI) staining. The number of Myo7a+ cells is small in all cochlear turns. Scale bars represent 50 μm. D The graphs show numbers of Myo7a+ cells in the cochlear turns on day 3, day 7, day 14, and day 28. The number of Myo7a+ cells in each cochlear turn of Pou4f3DTR/+ mice gradually decreases after DT injection. The biological sample number is 6 for day 3, 3 for days 7 and 14, and 4 for day 28. WT, wild type; DTR, diphtheria toxin receptor; DT, diphtheria toxin