Fig. 1. Zebrafish forebrain primary neuronal scaffold contains gata2::GFP-positive neurons. (A) 24 hpf zebrafish transmitted light view. The approximate location of the early neuronal clusters in the forebrain are schematically shown. (B) Schematic drawing illustrating the position of the major neuronal clusters and the axon tracts that connect them in the anterior CNS in zebrafish (based on Chitnis and Kuwada, 1990; Wilson et al., 1990; Ross et al., 1991). (C,D) Confocal images of dorsal (C) and lateral (D) views of a 24 hpf gata2::GFP zebrafish showing the location of GFP-positive cells in relation to forebrain morphology. The cells are located bilaterally (C) and occupy the rostroventral part of the diencephalon along the optic recess (or) (D). (E,F) Fluorescent confocal images showing the vrc stained with acetylated alpha tubulin antibody (red) to reveal the identity of gata2::GFP-expressing cells (green). White asterisk indicates a vrc cell with little or no GFP; black asterisk marks a GFP-positive vrc cell. White arrows indicate cells where colocalization of the neuronal antibody and the GFP can be seen (E). At 24 hpf all vrc cells express GFP and appear yellow due to spectral overlap between the green GFP and the neuronal antibody (F). Scale bar: 80 µm in A; 20 µm in C; 10 µm in D-F. tt, telencephalon; dc, diencephalon; drc, dorsorostral cluster; vrc, ventrorostral cluster; vcc, ventrocaudal cluster; ec, epiphysial cluster; SOT, supraoptic track; TPOC, track of postoptic commissure; POC, postoptic commissure; AC, anterior commissure; or, optic recess.