The zebrafish as a model system for the study of vertebrate development

Over the past ten years the zebrafish has emerged as a key model system for the study of vertebrate development. This has occurred primarily because of the promise of the system for developmental genetic studies, but, in addition to the necessary features of an animal which can be used for genetics, there are a range of experimental approaches which have proved successful in studies of tissue interactions and gene function. Such methods include cell transplantation and the analysis of gene function by injection of RNA or antibodies into the fertilized egg. The object of this review is to outline the main features of zebrafish development and the methods which have been used in order to identify and study the role of developmentally important genes.

It is important to point out that gene function analyses in the zebrafish, whether they be by mutational screens or RNA injection, are carried out against an increasing and extensive knowledge of basic embryology. Thus the transparency and rapid development of the embryo has been exploited to great effect by Kimmel and his colleagues in establishing a basic fate map (Kimmel, Warga & Schilling, 1990) using cell marking experiments in which flourescent dyes are injected into single cells. This kind of analysis has also led to a framework understanding of the lineage relationships of cells in the blastula and an assessment of the timing of cell fate lineage restrictions.