Fig. 6.

Expression of Atoh-Cre as revealed with a Rosa 26 line is shown for E18.5 embryo ears (A–D). Hair cells are most profoundly positive for the β-galactosidase reaction product (A, B, C) and can be seen in whole ears (A), flat mounted cochlea (B) or sections imaged with confocal microscope (C, level of section is indicated by dotted line in B). However, additional cells in the cochlea are also positive (A, B). Note that Atoh1-Cre staining can be shown in some spiral ganglion neurons (Spgl in A, B; SpglN in D) at any level of magnification (A, B, D). Note that the X-Gal reaction product deposited at places of β-galactosidase activity tends to form small deposits outside of cells (small blue specks in C) but is most prominently deposited in the cytoplasm of Atoh1-Cre positive cells like inner and outer hair cells and spiral ganglion neurons (C, D). Dotted line in B indicates the section plane with C, D indicated as squares. IHC, inner hair cell; OC, Organ of Corti; OHC, outer hair cell; S, saccule; Spgl, spiral ganglion; SpglN, spiral ganglion neuron; U, utricle Bar indicates 100 μm in A, B, 20 μm in C, D.