Nonsensory cells of the cochlear structure express a7 GFP As suggested by the preceding discussion, there was expression of a7 GFP by both neuronal and non-neuronal cells (Fig. 4) . This is particularly clear in the postnatal mouse (e.g., P6-P12), where the predominant expression of a7 GFP in neuronal cells was by cells of the SG (Fig. 4A) . The strongest labeling of cochlear structures was restricted to Hensen's cells and the spiral prominence ( Fig. 4A-E) . Evident at the P6 stage was a7 GFP signal in individual cells of the spiral ligament ( Fig. 4C and D) . Also evident were the extended branching that is characteristic of the morphology of type II fibrocytes located in this region (Fig. 4D ; Spicer and Schulte 1991; Sun et al. 2012 ). In the P12 cochlear structure, the branches were more abundant and form a 'feathered' structure that emanates from cell bodies defined by a7 GFP expression (Fig. 4E) . Cells of the stria vascularis or other members of the cell family composing the structures of the lateral wall and surrounding cochlear duct were not observed to express a7 GFP in these later stages of development (Fig. 4) .