(A, B, C–D′, F–H) Single section LSM of outer HCs of an Fltp+/+; Dlg3-Venus animal at E18.5 reveals that Dlg3-Venus is located at the lateral membrane and at the medial membrane (or the lateral membrane of the supporting cell) of IE HCs (A and B). Fltp is localized lateral to the cuticular plate (CP) and the stereocilia bundles (SC) (C and D). Dlg3-Venus is located in a lateral crescent overlapping with Fltp localization (C′ and D′). The unstained area marks the region of the BB (C′ and D′). Dlg3-Venus is co-localized with Dvl2 (G) at the most lateral membrane directly opposite of Vangl1 (F) and with ZO-1 at the apical membrane (H). (A′, B′, E, E′) IMARIS wireframe animation of a Dlg3-Venus IE HC showing Dlg3-Venus co-localization with the BB, the kinocilium, and actin (A′ and B′) and a Fltp+/+; Dlg3-Venus IE HC showing Fltp, Dlg3-Venus, and Phalloidin co-localization (E and E′). The actin network, the CP, and the SC are marked by Phalloidin (Phall), Fltp protein by Fltp116-1 (Fltp), the kinocilium by acetylated-Tubulin (aT), the BB by pericentrin (Peric), the apical cell membrane by ZO-1, core PCP proteins by Vangl1 and Dvl2, and Dlg3-Venus fusion protein by GFP. Scale bars; 2 µm (A–E′), 3 µm (F–H).