Figure 9  BDNF and NT-3 mRNA expression is shown in the cochlea of P0 (a-d) and P8 (e,f) Brn3c null and control littermates. Note the limited expression of BDNF in the basal turn of both wildtype and mutant littermates (a,b) and the much stronger expression of NT-3 in the apex over the region of the inner hair cells in both wildtype and control littermates (c,d). NT-3 expression persists at least until P8 in the apex of Brn3c null mice in an area that topologically compares to the inner hair cells of control animals (e,f, arrows). Bar indicates 100 μm.