Comparative analysis of neurulation: first impressions do not count.

The central nervous system of vertebrate embryos originates from the neural tube (NT), a simple epithelium surrounding a central lumen. The mechanisms underlying the shaping of the NT, a process otherwise known as neurulation, have been the focus of numerous studies, using a variety of model systems. Yet, it remains unclear to what extent neurulation is conserved across vertebrates. This review provides a comparison between modes of neurulation, with a focus on cellular mechanisms. An emerging concept is that cell behaviors reveal similarities between modes of neurulation that cannot be predicted from morphological comparisons. (c) 2009 Wiley-Liss, Inc.