Control of chromatophore movements in dermal chromatic units of blue damselfish—I. The melanophore

Abstract

1. 1. Mechanisms controlling pigment movements in the melanophore of the blue damselfish, Chrysiptera cyanea, were studied. 2. 2. Histological observations revealed that the melanophore had three-dimensionally developed processes to envelop overlying small iridophores, and thus participated in the construction of a simple dermal chromatophore unit. 3. 3. Nervous stimulation, catecholamines and melatonin brought about melanosome aggregation in the melanophore. 4. 4. The actions of the nervous stimulation and catecholamines were antagonized by alpha adrenolytic agents. 5. 5. A beta adrenergic agonist, metaproterenol, adenosine and adenine nucleotides, and alpha-MSH acted as pigment-dispersing agents. 6. 6. These results indicate that the melanophore of the present material is controlled quite orthodoxly by adrenergic nerves and endocrines, notwithstanding the fact that it has quite a unique morphology among fish species, and that its motile rate is remarkably high.