TABLE 1.
Properties of rostral and caudal hair cells of the frog AP
| Rostral | Caudal | References | |
|---|---|---|---|
| Frequency range of highest sensitivity | Low (<∼500 Hz) | High (∼500–1,200 Hz) | Lewis et al. 1982 |
| No. of active zones (synaptic sites) | 16/cell | 6/cell | Simmons et al. 1995 |
| Ribbons/synapse | 1 | 1–3 | Simmons et al. 1995 |
| Innervation pattern of afferent nerve fibers | Branched up to 9 hair cells/fiber | Unbranched (mostly) at most a few hair cells/fiber | Simmons et al. 1992 |
| Electrical tuning | Yes | No | Pitchford and Ashmore (1987) |
| Smotherman and Narins (1999, 2000) | |||
| Otoferlin, calbindin and parvalbumin | Yes | Yes | This study |
| Calretinin | No (mostly) some labeling of lateral edge hair cells | Yes | This study |
| Vesicles released/synapse (fast pool) | ∼4 | ∼11 | This study |
| Ca2+ dependence of exocytosis | Linear | Non-linear | This study |
| Frequency dependence of exocytosis | No | No | This study |
All properties illustrate differences between rostral and caudal hair cells, except for the lack of a frequency dependence of exocytosis in either hair cell type and the presence of otoferlin, calbindin and parvalbumin. Otoferlin and the calcium binding proteins (CaBPs) are found throughout the entire epithelium (see “Results”). The table only shows properties relevant to the discussion in this study and provides only a subset of known differences between hair cells of the rostral and caudal portions of the AP. See also Van Dijk et al. (2011) for comparison of other properties