Developmental neurobiology of the anterior areas in amphibians: urodele perspectives.

Because of its evolutionary grade and its relative simplicity, the Urodele brain provides an excellent archetype for the study of forebrain development. Early experiments on Primary Induction took advantage of the Urodele's manipulatability and ease of use, but due to the fact that its ectoderm was very readily neuralized Anurans (especially Xenopus) became the vertebrate of choice for early developmental neurobiology. Recent advances in the molecular biology of neuralization in Xenopus may rejuvenate Urodele use in solving the complicated sequence of events during this process of neural induction and to ascertain if separate or a combination of events (de fault and inductive) are involved. In the future, the combined use of Urodeles and Anurans will provide much information with regard to the evolutionary conservation of the mechanisms of regional specification, gene expression events, neurulation, neuroblast migration, and axonogenesis during the development of the nervous system. The present review provides some recent examples of this approach of using Urodeles and Anurans in a combinatorial fashion to decipher specific aspects of developmental neurobiology.