How do animals get the stripes? 　　　　　One of the most beautiful designs seen in the nature is the skin pattern of 　　　　　animals. Each species have its characteristic patterns, which is effective 　　　　　in some aims; hiding, mating, or mimicry. However, the most interesting and 　　　　　mysterious thing concerning the animal skin pattern is the mechanism how it 　　　　　forms. As tissues inside of the skin usually have no morphological 　　　　　similarity to the patterns, skins must generate the pattern by itself 　　　　　without any positional cue derived from other pre-existing structure. In 　　　　　1952, a British mathematician A. Turing presented a theoretical model that 　　　　　answers this question. He showed that a network of chemical (or cellular) 　　　　　reactions is capable of generating stable waves (reaction-diffusion wave), 　　　　　which can provide the positional information for the pigment pattern. We 　　　　　found that the skin patterns of some tropical fish rearrange exactly in the 　　　　　manner Turing's model predict, suggesting the mechanism of 　　　　　reaction-diffusion underlies the pattern formation. However, the molecular 　　　　　or cellular level mechanism of the phenomenon is still totally unknown. 　　　　　 　　　　　The zebrafish (Danio rerio) is strikingly patterned in bands that are 　　　　　composed of three types of chromatophores. Accumulating genetic data 　　　　　suggest that the pigment cells are responsible for the pattern formation. 　　　　　To know how the pigment cells interact one another, we used lasers to ablate 　　　　　specific populations of pigment cells and observed their re-growth. Process 　　　　　of the pattern regeneration differs depending of the position and sizes of 　　　　　the area where the pigment cells are depleted. This study suggested that 　　　　　there are two different types of interactions among the pigment cells, which 　　　　　satisfies the basic requirement of Turing's mechanism to form the stable 　　　　　stripe pattern.