A region of the vertebrate neural plate in which neighbouring cells can adopt neural or epidermal fates

Cells in the neurogenic region of the fly, Drosophila melanogaster, become either neural stem cells or epidermis and the selection of the former requires the activity of the proneural genes [1], In contrast, it is commonly thought that all cells in the vertebrate neural plate contribute to the neural tube and that consequently there is no need for the selection of individual neural precursors (e.g,, [2]), Here we present a detailed fate map of the chick caudal neural plate (CNP), a cell population that generates the posterior hindbrain and spinal cord. We show that this is a unique region of the neural plate where neighbouring cells can contribute to neural tube or epidermis, further, neural tube precursors leave the CNP in an approximate rostro caudal order and give rise to discrete portions of the neural tube where they or their progeny behave as neural stem cells [3]. Our data suggest that neural and epidermal cell fates are acquired on a cell by-cell basis within the CNP and thus in a manner strikingly similar to that in the fly. Indeed, the assignment of neural cell fate in this region may prove to be mediated by the functional homologue of the fly proneural genes (chick achaete-scute homologue 4 cash4), which is expressed heterogeneously within this cell population [4].