Imaging the cell biology of neuronal migration in zebrafish.

The migration of immature neurons from proliferation zones to their place of final differentiation occurs in many areas throughout the developing vertebrate central nervous system. As migration represents a key step in neuronal differentiation it has been modeled extensively in cell culture, matrix gels or explanted tissues. Due to the many complex interactions that are involved in this dynamic process, it would be ideal though to observe neuronal migration non-invasively directly in the developing organism. Furthermore, not only migratory pathways have to be characterized in detail, but also the underlying cell biology of neuronal migration needs to be revealed. For example, addressing how signal transduction is mediated into directed cellular movement at the level of different cellular organelles is not only crucial to understand the cellular and molecular interplay of dynamic brain differentiation but also to better reveal the etiology of neuronal migration diseases. Recent adbances in zebrafish conditional genetics and simultaneous multi-cistron expression combined with the progress in high-resolution high-speed bio-optics promise that neuronal migration can be resolved at unprecedented detail in this organism. Thus the stage is set in zebrafish for true in vivo cell biology. Which will allow for re-addressing the many models of neuronal migration derived from in vitro data of cultured cells or tissue explants. Hence zebrafish can serve to fuse the large fields of developmental genetics and cell biology in vertebrates