Fig. 1.

Sox2^CreERT2 mice have inducible Cre activity in type II hair cells and supporting cells. a-c Confocal images showing immunolabeling for Sox2 (red) and DAPI nuclear labeling (blue) in slices focused on the nuclei of type II hair cells (HCs) (a), type I HCs (a), and supporting cells (SCs) (c) of the utricular macula. d-e Confocal images of utricles from Sox2^CreERT2:ROSA26^tdTomato mice injected with tamoxifen, focused on either the macula (d,d) or the stroma (e). d and d show the same view, with labeling for tdTomato (Tom), myosin VIIa (Myo), and DAPI shown in d and Tom only shown in d. The yellow line in d shows the approximate position of the striola (S). The white boxes in d show the approximate regions sampled for cell counts for the Sox2Cre^ERT2 line and for all other lines that were quantitatively analyzed. TE = transitional epithelium. The arrow points to the TE near the notch. e shows Tom labeling in the stroma. f Utricle from a Sox2^CreERT2:ROSA26^tdTomato mouse that did not receive tamoxifen, focused on the sensory epithelium. g-h Confocal slices through the lateral extrastriolar region, with slices through the type II hair cell (HC) nuclear layer (g), the type I hair cell (HC) nuclear layer (g'), the supporting cell (SC) nuclear layer (g"), or the stroma (h). The arrow in g' points to a Tom-labeled type I HC. Scale bar in a = 5 μm and applies to a-c. Scale bar in d = 150 μm and applies to d-f. Scale bar in g = 5 μm and applies to g-h