Fig. 3

Co-expression of CXCR7 and SDF1 is restricted to a sub-population of neuroepithelial cell in r5. (A) Cross-sections at the level of r5 level at 19 hpf. Expression of sdf1a is intense in the germinal zone around the midline and is absent both in the dorsal region of the neural tube and in the floorplate. (B–D, F, G, I, J) Double insitu hybridization of sdf1a (green, B, F, G, J) and cxcr7b (red, C, F, G, I), the dotted line delimited the neural tube border and the dotted circle the notochord position. (C) cxcr7b is prominent in the ventral area of r5. The merge image indicates a co-expression in the ventral half of r5, arrows (D). (E–J) Expression patterns at 24 hpf. (E) Cross-section at the r5/r6 boundary (24 hpf) reveals sdf1a expression in the basal plate, most prominently within the periventricular region, with exclusion from the floor plate, arrows. (F) Double FISH after observation with Nomarski optic, which allow cell border visualization or confocal microscopy analysis (G). (I, J) Detection of cxcr7b (red) and sdf1a (green, arrows) in r5. (H, I) Cross-section through r5 shows that cxcr7b expression is restricted to a few cells adjacent to the floor plate, arrow. (J) Single merge image of a confocal Z-stack showing that both genes are expressed within the same cells (underlined, red and green spots). n = notochord, circle, ov = otic vesicle.