Fig. 7

Overview of the developing fetal inner ear from GW9 to GW15 along the basal turn. a Toluidine blue stained semi-thin section of a fetal human cochlea at GW9 showing the basal turn. Accumulation of epithelial cells is evident at this stage, but no differentiation in the supporting cells or hair cells is evident. b Toluidine blue stained semi-thin section of a fetal human cochlea at GW11 showing the basal turn. At this gestational age, supporting cells (arrows) show distinct morphological characteristics. c Toluidine blue stained semi-thin section of a fetal human cochlea at GW12 with the stria vascularis (asterisk) and supporting cells (arrows) evident. d Toluidine blue stained semi-thin section of a fetal human cochlea at GW13 with tunnel of Corti development starting. The developing outer and inner hair cells are also apparent (arrow) in the histological section. e Toluidine blue stained semi-thin section of a fetal human cochlea at GW14. The opening of the tunnel of Corti (arrow) is evident at GW14 with the outer and inner hair cells lining the developing OC being apparent (arrowheads). f Toluidine blue stained semi-thin section of a fetal human cochlea at GW15 the tunnel of Corti is enlarged (arrowhead). The cytoarchitecture of the stria vascularis (arrow) is well-developed. Melanocytes invading the basilar membrane in the future stria vascularis are also visible (arrowhead). Scale bars = 50 μm