Fig. 1. Sox8 expression in neural crest progenitors and their derivatives. (A) Sox8 is first detected at the gastrula stage in a ventrolateral domain around the blastopore. At stage 11.5 (B-D) Sox8 expression around the blastopore persists and additional expression is detected lateral to the neural plate (arrows). Vegetal (A), lateral (B,C; anterior towards right) and dorsal (D; anterior towards the top) views. Comparison of Sox8 (E) Sox9 (F) and Sox10 (G) expression in sibling stage 14/15 embryos illustrates that all three genes are expressed in the presumptive neural crest. Dorsal views, anterior towards the top. (H) Section of a stage 15 embryo illustrates the expression of Sox8 in both the lateral (arrows) and the medial neural crest (arrowheads). At stage 17 (I,J), Sox8 persists in the neural crest region and is also expressed anterior to the neural plate in the prospective cement gland (arrow). As the neural tube closes (K,L), Sox8 is detected in the migrating neural crest cells in the cranial region (arrows), and the premigratory cells in the trunk neural crest (arrowheads). Dorsal view, anterior towards top (I,K); lateral view, anterior towards the left (L); cranial view (J). (M) Comparison of Sox8, Sox9 and Sox10 expression at the tailbud stages. Dorsal views of stage 25 embryos, anterior towards the right. Sox8, Sox9 and Sox10 are co-expressed in the migrating cranial neural crest. Posteriorly, although Sox8 and Sox10 are both expressed in trunk neural crest cells, Sox9 is downregulated in this cell population. At stage 35 (left panels, lateral views), Sox8 is detected in the cranial neural crest similar to Sox9; however, at this stage, Sox10 starts to be downregulated in the branchial arches. Sox8, Sox9 and Sox10 are co-expressed in the otic vesicle at this stage (arrows). Ventral views (right panels) showing colocalization of Sox8 and Sox9 in the pancreatic rudiments (arrowheads) where Sox10 is not detected.