(A–D3) A wildtype neuromast (A) showing five A > P, four P > A (red asterisks), and two immature HCs (white arrows). A single neuroD:tdTomato-labeled afferent neuron (C) contacts four P > A myo6b:actb1-GFP HCs (red asterisks). (D1–D3) Selected optical sections showing nerve fibers (red) contacting cell bodies (green) of HCs (white arrowheads, 4/9 HCs). (E–H3) A single afferent neuron (G) contacting eight out of ten total P > A HCs (H–H3) in an emx2 ko neuromast (arrowheads). (H1–H3) Selected optical sections of (H). (I–L3) A single labeled afferent neuron (K) contacts four out of thirteen total HCs in an emx2 ko neuromast (arrowheads). (L1–L3) Selected optical sections of (L). (M–T) A single afferent neuron (O) contacts ten out of twelve A > P Gfp-positive HCs (M,N) in an emx2 gof neuromast (arrowheads). (P1–P3) Selected optical sections of (P). (Q–T2) A single afferent neuron (S) contacts three out of eleven total A > P HCs (Q, R,T) in an emx2 gof neuromast (arrowheads). (T1–T2) Selected optical sections of (T). The number of neuromasts: WT, n = 11; emx2 ko major, n = 8, minor, n = 4; emx2 gof major n = 12, minor n = 6. Scale bar = 10 μm.