Fig. 1

In vivo imaging and anatomy of the gerbil cochlear partition. a Experimental approach to the middle-ear, basilar membrane, and underlying structures of the cochlear partition in the round window region of the gerbil cochlea. b Vibration measurements are made by aligning the OCT beam with discrete points spanning the length (red dots) and width (blue dots) of the twisting, tilting, and spiraling cochlear partition (yellow). The measurement technique is sensitive only to vibration components that align with the near-vertical optical axis of each OCT beam. c OCT reflectance image (grayscale), with structural framework of Corti’s organ (yellow) superimposed for reference (cf. d, e). Scale bar (red), 0.1 mm. d Underlying anatomical structures. The hearing organ’s sensory cells are shown in dark blue, with key mechanical support cells and accessory structures in yellow. Thick black lines replicate elements of the main structural framework from c: the framework includes the collagen-rich arcuate and pectinate zones of the BM, the tubulin-rich inner and outer pillar cells that form the main (inner, triangular) tunnel of Corti, and the actin-rich reticular lamina (including the cuticular plates of the sensory inner and outer hair cells). e Map of vibration magnitudes evoked by a multi-tone stimulus at 70 dB SPL. Magnitudes are expressed on a logarithmic color scale, in decibels (dB) relative to the maximum root-mean-square magnitude of 10 nm. Measurement beam ordinates are indicated at the base of the map using gray arrowheads. b Boettcher’s cells, BM_AZ/PZ basilar membrane arcuate and pectinate zones, CAP compound action potential, dc Deiters’ cells, ISL inner (primary, osseus) spiral lamina, ihc inner hair cell, iss inner spiral sulcus, ohc outer hair cells, OSL outer (secondary) spiral lamina and ligament, ot outer tunnel of Corti, RM Reissner’s membrane, RWM round window membrane, sc support cells, SCC semicircular canal, sm scala media, st scala tympani, sv scala vestibuli, t tectal cells, tc tunnel of Corti (inner). Preparation RG16760, CF 40 kHz