Lateral Line Organ of Fish: A Possible Key to the Hair Cell Problem

The mechanics and physiology of the hair cells of the cochlea are very difficult to investigate for obvious technical reasons. The hair cells of the lateral line of fish are embryologically and morphologically very similar to the hair cells of the inner ear. The morphological similarity is so close, in fact, that it seems warranted to investigate the hypothesis that all these different hair cells behave physiologically in a similar way. The ear can be thought of as an invaginated lateral line organ with a middle ear of some kind attached to transform pressure waves into volume displacements. We find, however, differences as well as similarities. Morphologically, the lateral‐line organ of the killifish shows a curious polarization: in an oval patch of supporting cells, a strip of hair cells is embedded along the major axis. Physiologically, the organ is directionally sensitive along this axis, too. One remarkable difference is that, although the cochlear microphonic over a wide intensity range is proportio...