Fig. 1: The afferent neuronal innervation pattern is segregated across the LPR in the mouse maculae.
From: Function of bidirectional sensitivity in the otolith organs established by transcription factor Emx2
a Schematic of the segregated neuronal innervation pattern in maculae but the location of the segregation border is unclear. b Schematic illustrating the border of Emx2 expression domain (green) demarcates the LPR in maculae. A directional stimulus (arrow in inset) across the LPR simultaneously activates and inhibits two different groups of HCs. c, d Emx2 lineage domain (green) in the utricle (c, c’, n = 2) and saccule (d, d’, n = 2) of Emx2cre/+; RosatdTomato inner ears, which encompasses HCs with opposite hair bundle orientation from the rest of the macula based on anti-β spectrin staining (magenta). The location of the tallest rod of the bundle, the kinocilium, is devoid of anti-β spectrin staining54. The border of the lineage domain demarcates the LPR (yellow dotted line). e–h” Neuronal tracing using NeuroVue® Red (magenta)- and NeuroVue® Maroon (green)-soaked filter papers inserted into the brainstem and cerebellum of hemi-sectioned heads of wildtype (e–e”, g–g”, WT) and Emx2cre/+; RosatdTomato (f–f”, h–h”) embryos at E16.5, respectively. Neurons projected to the brainstem (e’, g’, magenta) and cerebellum (e”, g”, green) are segregated in the utricle (e, n = 5) and saccule (g, n = 3). White dotted line roughly separates most of the green and magenta dye labels. Limited dye labeling from the brainstem (f’, h’, magenta) is evident in the Emx2 lineage domain (f”, h”, green) of the lateral utricle and inner saccule (f, n = 2; h, n = 2). White asterisk in e–e” and g–g” represents regions that show mixed labeling of both dyes that has been described previously16. White asterisk in h–h” represents a dorsal–posterior region of the saccule and where Emx2 lineage domain expands beyond the LPR13, where the two dye labels overlap (g–g”, white asterisk). ac anterior crista, lc lateral crista, pc posterior crista, sac saccule, ut utricle. Orientation: D dorsal, L lateral, P posterior. Scale bar = 100 μm in c–h; 25 μm in c’, d’.
