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. 1999 Nov 15;19(22):9900–9912. doi: 10.1523/JNEUROSCI.19-22-09900.1999

Fig. 3.

Fig. 3.

Altered RGC axon trajectories at the ventral hypothalamus of DCC- or netrin-1–deficient mouse embryos. a, b, Each panel shows images of DiI-labeled RGC axons at the ventral hypothalamic region in wild-type (top, green), heterozygous (middle, green), and mutant (bottom, red) littermate E14 embryos. The retina of origin is toward the topleft,and the optic tract is toward the bottomright. The arrow indicates the orientation (anterior is at the top), and thewhitedot indicates the midline.c, The schematic diagram shows the location of the angles 1 and 2 measured in RGC axon projections, for example, shown here for the projections of wild-type (top) and mutant (bottom) embryos of a.d, The graph shows angles 1 and 2 in heterozygous (Het; columns 1 and 2) or mutant (Mut; columns 3 and 4) embryos compared with wild-type (WT) embryos at E14–E15. Data from netrin and DCC embryos have been pooled. The amount in degrees by which angles 1 and 2 in heterozygotes or in mutants exceed angles 1 and 2 in wild-type embryos is plotted on the y-axis.Asterisks indicate a significant difference was found in mutants (but not heterozygotes) compared with wild type (Student'st test; p < 0.002 for mutants;p > 0.2 for heterozygotes; n = 5 wild type, 9 heterozygous, and 10 mutants). Blackbars, angle 1; graybars, angle 2. e, In the chiasm of wild-type embryos, a subset of RGC axons (asterisk; shown as a negative image to highlight axons) crosses the midline posterior to the main RGC axon bundle. Theinset shows the outline of the main bundle in the chiasm (darkgray), and the redbox indicates the approximate region from which the image in e was taken. In many cases of netrin-1 or DCC mutant embryos, RGC axons crossed the midline at a point that correlates with this posterior region. f, DiI-labeled RGC axons at the ventral hypothalamus of E14 wild-type (green) and Pax6Seyneu/+ heterozygous (red) littermate embryos are shown. Although optic nerve size in Seyneu/+ heterozygous embryos is reduced, abnormally angular RGC axon trajectories such as those seen in netrin-1 or DCC mutants were not observed. g, The graph shows that angles 1 and 2 inSeyneu/+ heterozygous animals were not significantly different from those present in wild-type littermates (y-axis same as in d). Scale bars:a, b, f, 250 μm; e, 100 μm.