The sense of hearing depends on the faithful transmission of sound information from the ear to the brain by spiral ganglion (SG) neurons. However, how SG neurons develop the connections and properties that underlie auditory processing is largely unknown. We catalogued gene expression in mouse SG neurons at six developmental stages, ranging from embryonic day 12 (E12), when SG neurons first extend projections, up until postnatal day 15 (P15), after the onset of hearing. For comparison, we also analyzed the closely-related vestibular ganglion (VG) at the same time points.
To identify genes involved in SG axon guidance and branching, target selection, synaptogenesis, synaptic refinement, and synaptic function, we collected SG at E12 and E13, E16, P0, P6, and P15. We also collected VG at the same time points. For E12 and E13 time points, SG and VG were microdissected from Rnx-cre; Z/EG embryos, which express GFP in the VG. E16-P15 VG was also isolated by microdissection from Rnx-cre; Z/EG animals. E16-P15 SG neurons were isolated by FACS sorting dissociated cochlea from Mafb-GFP animals.