Fig. 1. Foxd3 expression in neural crest cells. (A-C) Immunohistochemical analysis of Foxd3 (green) and Pax3 (red) expression in E9.5 mouse embryos at thoracic (A) and cervical (B,C) levels. Foxd3 is expressed in presumptive premigratory and migrating neural crest cells and in dorsal midline cells. All the Foxd3 cells are also Pax3 positive (yellow). (D-G) Foxd3 expression in E10.5 mouse embryos. (D,E) Differentiating neurons in sensory (drg) and sympathetic ganglia (sg) were detected using an antibody to NeuN (red). (G) Peripheral axons were stained with an antibody to neuron specific-tubulin (TuJ1) (red). Foxd3 (green) is rapidly downregulated in differentiating sensory (D) and autonomic neurons (E) but is maintained in Schwann cell precursors that envelope the ganglia and axons. (F) Cross-sections of embryos pulsed with BrdU for 90 minutes, and triple stained with BrdU (red), Foxd3 (blue) and Islet1 (green). BrdU-positive/Foxd3-positive cells (pink) are found encompassing and within the DRG (arrows); however, none of these cells co-expressed Islet1 (green) a marker of postmitotic sensory neurons. (H,I) Foxd3 (green) is expressed in melanocyte precursors migrating beneath the ectoderm at E12.5 (arrows). (H) The ectodermal layer is stained with ß-catenin (red). (I) Foxd3-positive/Pax3-positive cells (yellow) envelope the dorsal root ganglia (arrowhead). Foxd3-positive crest cells are also observed migrating along a dorsolateral pathway beneath the skin (arrow). dm, dermomyotome; drg, dorsal root ganglion; mn, motor neurons; nt, neural tube; sc, spinal cord; sg, sympathetic ganglion; sk, skin; vr, ventral root.
