slit and sema3d expression in wild type and yot(gli2) mutants. (A-J) Triple (A-F,I,J) and double (G,H) labeling shows mRNA expression (red) in relation to axons (anti-AT, blue, not shown in C and D) and glial cells (anti-Gfap, green) in the commissural region of the forebrain at 27 hpf in wild type (A,C,E,G-I) and mutants (B,D,F,J). (a-f) Single confocal slices through the preoptic and POC/chiasm region (boxed in A) from superficial (top) to deep (bottom). (A,C) slit2 and slit3 expression is mostly absent from the pre-optic area, the POC/chiasm region (lower bracket), and the AC region (upper bracket) in wild-type embryos. Dotted lines show borders of expression. (E) Slit1a is expressed in complementary domains to slit2/slit3 and is present in the pre-optic area (between dotted lines). (G,H) Higher power single 0.56 μm confocal slices of wild-type embryo showing frontal (G) and lateral (H) views of slit1a expression (red) in the pre-optic area and the glial bridge cells. Gfap+ fibers appear to overlap with slit1a expression (arrowheads). The asterisk marks the same nucleus in both panels. Orange lines indicate the position of cross section in other panels. (I) Sema3d is expressed at the midline from the POC (lower bracket) to the optic recess. (B,D) In yot (gli2DR) mutants, slit2 and slit3 expression is expanded into the POC/chiasm region (dotted line shows the border of expression in the pre-optic area). (F) Unlike slit2 and slit3, slit1a expression is reduced in the POC/chiasm region of yot (gli2DR) mutant embryos. (J) sema3d expression is absent in the pre-optic area of yot(gli2) mutants. All panels except H show frontal views of the forebrain, anterior up. Scale bars: 10 μm.
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