Local light stimulation of melanophores of a teleost, Zacco temmincki

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Abstract
Responses of melanophores of the teleost, Zacco temmincki, to local light stimulation were examined in preparations of isolated scales. The melanophores induced the aggregation of melanosomes in darkness and their dispersion in light. Local illumination of a melanophore in the melanosome‐dispersed state inhibited centripetal migration of melanosomes only in the stimulated area. Local illumination of a pigment‐free branch of a melanophore with aggregated melanosomes generally brought about pigment dispersion into the stimulated area. However, when that area was at a significant distance from the edge of the central melanosome mass, the melanosomes never migrated into the irradiated area. Local illumination of the centrosphere of a cell inhibited the full aggregation of melanosomes in the dispersed and aggregated state. The degree of the inhibition depended on the size of the irradiated area. The result suggest that photoreceptive sites are distributed over the whole of a cell, and that the movements of melanosomes are regulated locally in a very precise manner.