Fig. 3. Expression of tfap2a during development of zebrafish embryos. (A-F) tfap2a is expressed widely at 24 hpf in (A) spinal cord neurons, the pronephric duct and widely in the epidermis; in (B) neural crest cells in the arch primordia; in (C) migrating posterior lateral line primordium; in (D) epidermal cells surrounding the olfactory vesicle; in (E) segmentally arranged cell groups in the lateral hindbrain; and in (F) bilateral clusters of cells in the tegmentum. (G,H) Expression of tfap2a is increased in the central nervous system at 48 hpf. (G) tfap2a is expressed in the telencephalon, tectum, pretectum and tegmentum. (H) Two laterally stripes of hindbrain neurons express tfap2a. The white arrowhead indicates the lateral and the black arrowhead indicates the more medial stripe of the tfap2a expression domain. In the isthmus, expression of tfap2a is not detected, while strong expression is established in the adjacent optic tectum and cerebellum. (I) The cells in the inner nuclear layer of the retina express tfap2a. (J) The lateral line organs express tfap2a. (K,L) At 72 hpf, a few cells adjacent to the forming gut tube express tfap2a. which are probably neurons of the sympathetic ganglia. (L,M) Higher magnification of the area adjacent to the gut tube where sympathetic ganglia form (72 hpf and 96 hpf respectively; arrowheads indicate tfap2a-expressing cells). (A-M) Anterior towards the left; (A-D,G,I,J) lateral views; (F,H,K-M) dorsal views. ap, arch primordia; ce, cerebellum; ep, epidermal cells; epi, epiphysis; hb, hindbrain; i, isthmus; inl, inner nuclear layer of the retina; llp, lateral line primordia; nm, neuromast cells; ot, otic vesicle; ov, olfactory vesicle; pnd, pronephric duct; sc, spinal cord; symp, cells of sympathetic ganglia; teg, tegmentum; tec, tectum.