The sensory hair cells of the inner ear of fishes are very similar to those found in the ears of al other vertebrates, as well as in the lateral line. Indeed, the vertebrate sensory hair cell evolved in the most primitive fishes, as we discussed in a review paper by Coffin et al. (2004). Over the course of multiple papers, my lab explored the detailed structure of hair cells, as discussed below. .

Ultrastructure of sensory hair cells - We have examined sensory hair cells using transmission electron microscopy (TEM) to look at both structure and innervation of the cells. Over the course of our studies, we have demonstrated that many fishes have multiple types of sensory hair cells (presumably for functional reasons), just had been previously demonstrated in mammals and many other terrestrial vertebrates. We also showed that each sensory cell is innervated by multiple fibers of the eighth cranial nerve, and that many cells have both afferent and efferent innervation.

Hair cell orientation patterns - A major contribution from our lab has been the demonstration that the hair cells on the otolithic end organs (saccule, lagena, utricle) are organized into various orientation groups, and that these patterns vary by species. The patterns, at least in the saccule, seem to be related to hearing capabilities. We also proposed (as have several other labs) that these orientation patterns are related to. the mechanism fishes use to determine sound source direction.

Hair cell proliferation and regeneration - Following the discover by Jeffrey Corwin that there was a large proliferation of sensory hair cell in the ears of elasmobranchs, we examined the ears of fishes and found the same phenomenon. This means that, unlike mammals that have all of their hair cells at birth, fishes continue to add hair cells as long as they grown. In addition, we demonstrated that if hair cells in fishes are damaged by ototoxic drugs or by loud sounds they be repaired or regenerate.

Ciliary bundles variation