Fig. 2.
Nrp1 and Sema3a expression during trunk NCC migration. Whole-mount in situ hybridization (ISH) for Sox10 (A and B), Nrp1 (C and D), and Sema3a (E and F) of 9.25 dpc (20–21 somite stage) mouse embryos. (A and C) Trunk NCCs express Sox10 and Nrp1 and migrate into the anterior sclerotome (black arrowheads), while the posterior sclerotome remains NCC-free (brackets); the arrows indicate the region where the sympathetic chain begins to assemble. (E) Sema3a was expressed in pairs of vertical stripes, 1 in the anterior (empty arrow) and 1 in the posterior somite half (empty arrowhead). (B, D, and F) Transverse sections through the wholemount samples shown in A, C, and E at the level of the anterior somite suggested that Sox10 (B) and Nrp1 (D) were co-expressed in NCC in the migration staging area (MSA), within the sclerotome (black arrowheads) and in NCC clusters (black arrows) adjacent to the dorsal aorta (da). Nrp1 expression in Sox10-negative mesenchymal cells (wavy arrow; compare B with D). (F) Sema3a expression in the forelimb (fl) and the dermomyotome (dm). (Scale bars: A, C, and E, 250 μm; B, D, and F, 100 μm.)