S-100 protein is a selective marker for sensory hair cells of the lateral line system in teleosts.

The distribution of S100 protein in the neuromast of the lateral line system (LLS) was investigated immunohistochemically in alevins of three species of teleosts (Salmo trutta, Salmo salar and Dicentrarchus labrax), using a polyclonal antibody. In both the neuromasts of the canals, as well as in the pit organs, the hair cells, regarded as the specific sensory cells, displayed cytoplasmic immunoreactivity for S100 protein. Conversely, the supporting cells, mantle cells and basal cells were devoid of immunoreaction. These results demonstrate for the first time the occurrence of S100 in the LLS of teleosts. Due to the cell specific localization, this protein might serve as a marker for sensory hair cells in neuromasts. Copyright 2002 Elsevier Science Ireland Ltd.