Figure 2.

Ear afferent innervation of the spinal cord (A) 3D reconstruction of an ear transplanted adjacent to the spinal cord labeled with antibodies against Tubulin (green) and MyoVI (red) displaying neurons and hair cells, respectively. (B–C) Single optical sections of an X. laevis brain and spinal cord (blue, autofluorescence) in the dorsal (B) and ventral (C) plane following injection of dye (green) into an adjacently transplanted ear shows afferents entering the spinal cord dorsally and ventrally, respectively. White arrowhead indicates the entry point of inner ear afferent projections. (D) Lateral view schematic diagram showing the position of the transplanted ear and the defined midline position (blue dotted line) along the dorsal-ventral axis of the spinal cord used to assign entry and projection planes of labeled afferents in B–C. (D′) Analysis of entry point and plane of projection for animals with ears transplanted adjacent to the spinal cord. Serial optical sections were analyzed for entry point of labeled fibers (dorsal, midline, ventral) and for plane of projection (dorsal, ventral). n = 20. (E) Backfilling of inner ear ganglion cells in an ear adjacent to the spinal cord from dye injection into the spinal cord rostral to the transplanted ear. (F) Backfilling (red) of inner ear ganglia and peripheral afferent processes on hair cells in an ear adjacent to the spinal cord from dye injection into the spinal cord. Hoechst nuclei counterstained in blue. Spinal Cord, SC; Hindbrain, HB; Dorsal, D; Ventral, V; Rostral, R; Ganglion cells, G; Utricle, U; Saccule, S; Lagena, L; Anterior canal, Ac; Horizontal canal, Hc; Posterior canal, Pc. Scale bars are 100 μm. [Colour figure can be viewed at wileyonlinelibrary.com]