During mouse embryogenesis, the anterior ectoderm develops into neural derivatives (the forebrain) and non-neural derivatives (the cephalic non-neural ectoderm). On p. , Kirstie Lawson, Anne Camus and co-workers use single-cell labelling and gene expression analysis to provide new insights into this cell fate choice. At late gastrulation, they report, the expression patterns of anterior ectoderm genes overlap significantly and correlate with areas of prospective fate but do not define lineages. They show that the rostral limit to forebrain contribution is more distal than previously reported. Finally, they report that some precursors of the anterior neural ridge, a signalling centre that is involved in forebrain development and patterning, are clonally related to neural ectoderm and are dispersed over a broad area of the anterior ectoderm where neural precursors also reside. Together, these results suggest that, although the segregation of neural and non-neural cells in the anterior ectoderm is incomplete at the gastrulation stage, there are elements of regionalisation in this tissue that preconfigure the organisation of the head.
