Foreword

Summary

The development of an organism from a single cell, the fertilized egg, is one of the most marvelous and beautiful of all nature's creations. The last decades have seen an explosion in our understanding of the mechanisms involved in development, largely due to the application of the techniques of molecular biology. The language of cells is molecules.

The neural crest presents us with a system in which almost all the basic features of development are present – pattern formation, determination, directed migration, and differentiation. It is truly remarkable in the diversity of cell types to which it gives rise – neural, mesenchymal, endocrine, and pigment – and all these end up away from their site of origin. Its development requires to know how genes control the behavior of the cells. We need to know to what extent the crest's diversity is laid down early on and to what extent it is multipotential. We also need to know the role of intrinsic developmental programs and their relation to external signals. A particular problem with the crest is how its migration to specific sites is directed. The creation of the crest during vertebrate evolution was a major event and has profound implications for human development.

The early understanding of the development of the crest relied on the techniques of classical embryology, such as removal of the crest from the early embryo and noting the effects, but a crucial step was the ability to mark the neural crest population reliably and so follow their development.