FIG. 5.

Commissural axon projections are defective in Trio-null embryos. (A) In the upper frames, trajectories of commissural axons are visualized using anti-DCC antibodies in sections of Trio^+/+ or Trio^−/− E11.5 embryos. The lower frames show enlargements of the corresponding images. Scale bar, 80 μm. (B) On the left is a schematic representing normal commissural axons that project from the dorsal spinal cord toward the ventral floor plate. In Trio^−/− embryos (right), commissural axons are defasciculated when they reach the ventral floor plate (arrows in both A and B). (C and D) The thickness of axon bundles in the dorsal and ventral spinal cords was quantified by measuring the width of the DCC-stained axons (red) relative to the width of the spinal cord (blue) as depicted in panel D. (E and F) Axon defasciculation in Trio^−/− embryos was quantified by measuring the DCC-stained area (red) relative to the total area of the spinal cord (blue) as depicted in panel F. P < 0.001, Student t test. Error bars represent standard deviations (n = 5 for +/+ and n = 7 for −/− embryos).