Fig. 8. Immunohistochemical detection of FGFRs in vivo and in cultured neural crest cells. In transverse sections of mesencephalic region of stage 9 quail embryos (n=3 for each category) FGFR1 (A) FGFR2 (B) and FGFR3 (C) are expressed ubiquitously but staining is particularly intense in the apices of the neural folds (arrows in A). (D) Control section stained with non-immune serum shows no staining. Scale bars, 100 µm. (E-H) Neural crest cells in culture (n=4 for each category). FGFR1 (E), FGFR2 (F) and FGFR3 (G) are all expressed by neural crest cells in culture. (H) Control culture stained with non-immune serum is negative. Scale bar: 50 µm. ect, ectoderm; end, endoderm; m, mesoderm; n, notochord.