Figure 1

Nrp1 and Nrp2 are expressed in different populations of cranial NCCs. (A-I) Whole mount in situ hybridisation of E8.5 to E9.5 wild-type embryos to determine the expression profiles of Nrp1 and Nrp2. (A, D, G) Sox10 labelled all migrating cranial NCCs and defined the r2 (open arrowhead), r4 (closed arrowhead) and r6 populations at E8.5, E9.0, and E9.5 as well as the otic vesicle (ov) at E9.5. (B, E, H) Nrp1 was specifically expressed in the r4 stream of NCCs and not in the r2 stream. (C, F, I) Nrp2 expression was restricted to the r2 stream of NCCs and was lacking in the r4 stream at E8.5 and E9.0. At E9.5, low levels of Nrp2 could be detected in the tissue ventral to r4. (J-U) Transverse in situ hybridisation sections of E8.5 embryos through the regions of the r2 and r4 streams counterstained for the neurotrophin receptor p75. (J-M) Sox10 and p75 identified all migrating NCCs. p75 staining was also evident in the epithelia in close association with migrating NCCs in the region ventral to r4. (N-Q) Transverse sections confirmed that Nrp1 is specifically expressed in the r4 NCC stream as well as the developing heart and cranial mesoderm (cm). (R-U) Transverse sections confirmed that Nrp2 was restricted to the r2 stream of NCCs as well as the neural tube, cranial mesoderm, and developing heart. IS, in situ hybridisation; e, eye; h, heart, r2, rhombomere 2; r4, rhombomere 4; ov, otic vesicle; e, eye. Scale bar = 100 μm.