What insights into vertebrate pigmentation has the axolotl model system provided?

Amphibians have been judiciously exploited by developmental biologists for many years for studying basic developmental mechanisms in vertebrates. In this review, the contributions that have been made by urodeles, in particular the axolotl (Ambystoma mexicanum), to the study of pigment cell biology are elaborated. Pigment cell differentiation is described, and the wild-type pigment phenotype is contrasted to pigment mutants such as albino, axanthic, melanoid, and white. Methods used for studying pigmentation, including recently developed molecular biological tools, are included to illustrate the significance of the axolotl as a model system for studying vertebrate pigmentation.