Figure 2

TrkB-expressing neural crest cells migrate with sympathetic neurons at stage 27, or late E5. (A) Transverse section of St. 27 (late E5) chick embryo spinal column region. At this stage, a stream of Hu C/D-positive cells (white) and TrkB-positive cells (green) are found in the region surrounding the dorsal aorta (DA) and ventral to the neural tube (NT), dorsal root ganglion (DRG), and notochord (NC). (B, C, D) St. 27 sections stained for TrkB (green) and a marker of neural crest cells, HNK-1 (red). In migrating clusters of TrkB-positive cells, HNK-1 is co-expressed. (E, F, G) St. 27 sections stained for Hu C/D (green) and tyrosine hydroxylase (red). All of the migrating neurons and some of the surrounding cells express tyrosine hydroxylase. (H) TrkB (green) is only expressed in cells adjacent to Hu C/D-positive cells (red), (I, J) TrkA and TrkC (both green) are expressed in both Hu C/D-positive (red) migrating cells and in surrounding cells. The box in (A) indicates the region where we obtained high power images. Calibration bars: Low power image: 200 μ; high power images: 20 μ.