Fig. 1. Cell cycle genes are downregulated as neuronal determination genes are upregulated in the CMZ of stage 41 Xenopus embryos. In situ hybridisations to identify expression of the genes indicated on each panel. C,I,O,U,F,L,R and X are overlaid images of the single hybridisations. In A the dashed line indicates the end of the CMZ and the solid lines, the boundaries between differentiated layers. Brackets indicate regions of co-expression.