Fig. 2

spon1b:GFP expression in cell populations from 48 to 96 hpf in telencephalic, diencephalic and hindbrain regions. Abbreviations: Hb, Habenula, dHb, dorsal habenula, TeO, Optic tectum, nMLF, Nuclei of the Medial Longitudinal Fasciculus, FO, Flexural Organ, a, Anterior, P, Posterior. a MIP color coded for a depth of 250 µm at 48 hpf. Cells in blue are part of the TeO. Cells in yellow are part of the developing Hb complex. Gamma was adjusted to a value of 0.75. b MIP color coded for a depth of 200 µm at 72 hpf. Cells in dark blue are part of the TeO. Cells in light blue are part of the developing Hb complex. Gamma was adjusted to a value of 0.75. c MIP color coded for a depth of 250 µm at 96 hpf. Gamma was adjusted to a value of 0.75. d MIP obtained from a 60 µm slice showing spon1b:GFP neurons in the hindbrain at 48 hpf. Rhombomeres (r3–6) are estimated by the position relative to the otocyst (oto). e MIP obtained from a 75 µm slice showing the Hb and the fasciculus retroflexus (red arrowheads) at 72 hpf. White asterisks indicate eye position. f Single plane showing an increased innervation at 96 hpf (red arrowheads). g Composite image of two MIPs obtained from a depth of 5 µm (cyan, depicting the vHb) and 20 µm (magenta depicting the dHb) at 48 hpf. Axons from the developing dHb are observed to project caudally, neighboring the nMLF (white arrows). Axons from the developing vHb project more caudally (white arrowheads), compared to axons from the dHb. Note the axons present within the tectal region. h Graph showing the average distance traveled by cells in the Hb subnuclei. The total distance traveled is significantly different (Mann–Whitney test, P value 0.0061) between cells in the dHb and the vHb subnuclei.. a–d, f–g are dorsal views. e is a lateral view