Shh expression in the FP is reduced in Arx-deficient mice. A) Shh immunostaining (bottom) in the FP of the spinal cord, but not in the notochord (arrowhead) is reduced in Arx−/y mice compared to Arx+/y. Note a similar reduction is detected in Alcam (another FP marker) immunostaining. The numbers below each image indicate the quantitative intensity of the signal in the FP relative to the signal in the notochord. The intensity is measured by area intensity of plot profile in Image J. B) Olig2, Shh induced gene, immunostaining show reduced expression in the mutant mouse spinal cord at E11.5 (top) and E14.5 (bottom). C) The quantification of the Olig2 immunostaining (representative images are shown in B) demonstrate that the number of Olig2+ cells is reduced in the mutant mouse spinal cord at E11.5 and E14.5 (n=3 mice per each). Error bars represent the SEM (p=0.0014 for E11.5 and p=0.086 for e14.5, two-tailed, unpaired t-test). Scale bars are 50 μm.