The lateral subnuclei of the habenulae are enlarged in c163 mutants. (A) Diagram depicting the relative expression patterns of genes in the epithalamus. (B) Kctd12.1 protein is detected in more cells of the left LsDh of the dorsal habenula than the right. (B′) By contrast, c163 mutants exhibit more Kctd12.1 neurons in both habenulae, particularly the right. (C) In wild-type larvae, the LsDh (green dashed line) includes a large, round soma-free area on the left but a smaller soma-free area on the right (white arrows). (C′) In c163 mutants, both the left and right habenula contain large cell-free areas (two are seen in the right habenula of this example). (D) In WT larvae, neurons of the MsDh express Kctd12.2, and are more abundant in the right dorsal habenula than the left. The soma of the Kctd12.2+ neurons are outlined in red (based on nuclear staining by ToPro3 [not shown]). Kctd12.2 expression is also detected in the extensive dendritic branches of MsDh neurons in the left habenula. (D′) In the dorsal habenulae of c163 mutants, the number of cells expressing Kctd12.2 is reduced. (E) nrp1a is expressed in a lateral portion of the LsDh of wild type embryos. (E′) nrp1a expression is expanded in the right habenula of c163 mutants. (F–F′′′) Axons from neurons expressing Kctd12.1 (green) target neurons of the dorsal and ventral IPN, which express somatostatin1.1 (sst1.1; red in F,F′) in WT embryos. (G–G′′′) In c163 mutants, Kctd12.1-expressing projections are confined to the ventraldomain of the IPN (white bracket: G′′′). All images are dorsal views at 4 dpf, except F′, F′′′,G′ and G′′′, which are lateral views. B, D, and F are 3D reconstructions of confocal z-stacks. C, C′ are single z-plane images from confocal z-stacks. LsDh: lateral subnucleus of the dorsal habenula. MsDh: medial subnucleus of the dorsal habenula. FR: fasciculus retroflexus. IPN: interpeduncular nucleus. Scale bars: (B–D = 30 μm; E = 10 μm; F′′ = 20 μm).
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