Fig. 7

SPX1 and GALR2a/2b expression in the habenula and interpeduncular nucleus. Transverse sections of the adult zebrafish brain, dorsal to the top. (A–C) In situ RNA hybridization in the adult brain with spx1 (A), galr2a (B), and galr2b (C) RNA. (A) Arrows indicate the expression of spx1 mRNA in the habenula. Black arrowheads indicate galr2a and galr2b mRNA expression, respectively, in the IPN (B,C). (D,D’) Transverse sections of the habenula (D) of Tg(spx1:mCherry-CAAX); Tg(pou4f1-hsp70l:gfp) zebrafish. (D) White, green, and blue dotted lines mark lateral and medial subdivisions of the dorsal habenula and ventral habenula, respectively. (D’) is a high magnification image of the box area in (D). White arrowheads indicate pou4fl⁺ spx1:mCherry-expressing cell body in the dHbM. (E–G’) Transverse section of the Hb (E,E’), FR (F,F’), and IPN (G,G’) of DiI-labelled Tg(spx1:mCherry-CAAX) zebrafish. Panel E’–G’ are high magnification images of white boxes in panel E–G. Yellow dotted lines mark DiI-labelled Hb (E), FR (F), and IPN (G). White arrowheads indicate that co-localization of DiI and mCherry fluorescence. (H–I”) Transverse sections of Tg(spx1:mCherry-CAAX); Tg(galr2b:egfp) zebrafish, which were labelled with DAPI. White, magenta, and yellow dotted lines mark the dorsal, intermediate, and ventral IPN, respectively. (H–H”’) Section views labelled with anti-galanin antibody. White arrowheads indicate the intermediate and ventral IPN, where spx1:mCherry⁺ axonal projections were observed. (I–I”) Panel I’ and I” are high magnification images of white and yellow boxes of panel I, respectively. White arrowheads indicate close contacts between EGFP⁺ cells and mCherry⁺ nerve fibres. Abbreviation: FR, fasciculus retroflexus; Hb, habenula; IPN, interpeduncular nucleus; Scale bar: 50 μm in A–I. 10 μm in D’–I”.