Fig. 5. Directional asymmetry influences IPN projection pattern. Habenular projections onto the IPN in sections (150 µm) through adult midbrain of (A-C) WT and (D-I) spaw MO-injected fish, which as larvae had a left (D-F) or right (G-I) positioned parapineal. (A-F) Axons originating from left habenula innervate dorsal and ventral IPN domains, while those from the right habenula only project ventrally. (G-I) In fish with reversed epithalamic laterality, L-R origin of IPN projections is also reversed, such that axons from left habenula now innervate only the ventral IPN. A-C are higher magnification Leica MZFLIII images of the same brain as in Fig. 4. D,E and G,H were imaged using a Leica SP2 confocal microscope and merged to produce the composite images in F,I. Dorsal is at the top in all images. Scale bar: 60 µm.