Fig 7. Expression of Sox2, Sox10, Gata3, Prox1 and Peripherin during primary auditory neuron development and maturation.

This schematic illustrates the expression of Gata3 (green), Sox2 (blue), Sox10 (brown), Prox1 (purple) and Peripherin (pink) as cells transition from the proneurosensory stage in the developing embryo, to the maturation of PANs in the spiral ganglion. Downward and upward inflections indicate the corresponding decrease and increase in expression, respectively. At E10.5, Sox10 was downregulated as neuroblasts delaminated from the otocyst. At E12.5, Sox2 expression was similarly downregulated and Prox1 began to be expressed in these cells. At E17, Peripherin started to become expressed. At P1, Sox2 was upregulated and maturing PANs began to differ in gene expression as they differentiated into their respective subtypes. All PANs expressed NF200, but only type I PANs strongly expressed TuJ1. Type I PANs downregulated Gata3 early and subsequently downregulated Sox2; however, Prox1 continued to be expressed. Type IIA PANs continued to express Gata3 strongly in adulthood and maintained expression of Peripherin while downregulating both Prox1 and Sox2. Type IIB PANs had a similar expression pattern to type IIA PANs but diverged when they started to downregulate Peripherin.