Fig. 3. Neural crest expression of neuropilin 2a1 and an unknown gene. (A-C'''), Neuropilin 2a1 expression is specific to cranial and trunk neural folds and dorsal neural tube (premigratory neural crest; white arrowheads), migratory cranial neural crest (black arrowheads) and somites. (D-F'') A gene with no homology to any sequences in the GenBank nr database is highly specific to neural folds from their earliest appearance and down-regulated at the time of neural crest migration. Expression is also apparent in splanchnic mesoderm (asterisk). (A,D) 4-somite embryo; (B,E) 7-somite embryo; (C,F) 12-somite embryo. Dorsal view, anterior up. (B'-C''',D'-F') Transverse sections (dorsal up) through embryos pictured in A-F at the levels indicated by lines. nt, neural tube; np, neural plate.