Somatotopy of the lateral line projection in larval zebrafish.

We examined the topography of the lateral line primary projection in zebrafish larvae by double labeling. The projections of two identified neuromasts of the posterior lateral line are seen as two separate sets of fibers that show reproducible spatial relationships: the projection of the anterior neuromast is always ventrolateral to that of a more posteriorly located neuromast. The same rule applies to the projection of anterior lateral line neuromasts. The position of the neuromasts along the antero posterior axis of the fish therefore is represented in the central projection of the sensory neurons. This somatotopy is similar to, and may be at the origin of, the tonotopic projection of the cochlear hair cells in mammals.