Dynamics of Peripherin (PRPH)-positive and class III β-Tubulin (TUBB3)-positive neurites during first hair cell differentiation. (A,B) Basal turn of a W10.4 (week 10 and 4 days) cochlea immunostained for (A) PRPH (green) and TUBB3 (red) and (B) MYO7A (red). (C,D) Apical turn of a W12 cochlea immunostained for (C) PRPH and TUBB3 and MYO7A (D). (C′) Magnification of the prosensory domain in (C). (E,F) Middle turn of a W12 cochlea immunostained for (E) PRPH and TUBB3 and (F) MYO7A. (G,H) Basal turn of a W12 cochlea immunostained for (G) PRPH and TUBB3 and (H) MYO7A. Cell nuclei were visualized with DAPI (blue). Bracket, the prosensory domain/OC; arrowhead, inner hair cell; white arrow, PRPH-positive growth cone; black arrow, TUBB3-positive growth cone; yellow arrow, PRPH/TUBB3-positive neurite. Abbreviations: KO, Kölliker’s organ. Scale bars = (A-C, D-H) 20 μm or (C′) 5 μm.