Fig. 3. The BMP inhibitor noggin prevents the development of the ciliary ganglion. After unilateral implantation of noggin-expressing CHO cells in E2 chick embryos the ciliary ganglion, as shown by expression of SCG10 (A), Cash1 (B), Phox2b (C) and VAChT (D), is absent at stage 24/25 (white arrowheads, A-D). In parallel, the development of the eye is strongly reduced (A-F left side; compare with normal right side). Sox10-positive neural crest cells aggregate at the position of the ciliary ganglion (black arrowhead, F), but remain undifferentiated (SCG10-negative) on the noggin-treated side (white arrowhead, E). Unilateral ablation of the optic vesicle in E2 chick embryos also prevents eye development (G,H; white asterisks; compare normal contralateral eyes, black asterisks), but does not affect ciliary ganglion formation as demonstrated by SCG10 and Phox2b expression in the CG (G,H). The SCG10-positive structure adjacent to the CG in (G) is an enlarged oculomotor branch of the trigeminal ganglion, frequently observed in eye-ablated embryos. Scale bar: 1 mm.