Expression of prdm1 in the nervous system of wildtype and mutant nrd zebrafish embryos. Lateral views (A, B) and dorsal view(C–H) where anterior is to the left, except in A and C where anterior is to the top. (A) At 90% epiboly, expression is observed along the border of the neural plate where neural crest cells and RB sensory neurons are being specified (arrow), more strongly at the anterior-most border. At tailbud stages (B), expression remains high at the neural plate border (arrows). The expression is particularly strong at the anterior border at tail bud stages (C). (D) At 11 hpf, expression is high at the lateral edge of the neural plate (arrow; higher magnification in E), and also is expressed ventrally in the adaxial cells (A) adjacent to the midline. (F) By 13 hpf, the expression at the border of the neural plate remains only in the most posterior region (arrow). (G, H) Analysis of prdm1 expression in nrd mutant embryos at 11 hpf. Low (G) and high (H) magnification images of nrdm805 embryos showing reduced expression of prdm1, especially at the neural plate border (arrowheads in G). A slight reduction in expression is also observed in the ventral adaxial cells (A). Abbreviations: wt, wildtype; nrd, narrowminded mutant embryos; A, adaxial cells. Scale bar is 50 μm.