The goal of our research program is to understand at the cellular and molecular level processes involved in early vertebrate development. We use the zebrafish, Danio rerio, as a model system because it allows combining genetic, embryological and molecular approaches. In the zebrafish, as in many other animal species, all developmental processes that occur prior to the activation of the zygotic genome at the mid-blastula transition, as well as some processes that occur after this transition, are driven by maternal factors stored in the egg during oogenesis. We use an interdisciplinary approach, spanning genetics, microscopy, bioinformatics and modeling, to understand how early embryonic process, from the cytoskeleton to gene expression, are integrated to generate the basic body plan. A primary focus of our research is on the functional diversification of cell types, particularly but not exclusively the development of the germ line.