Fig. 3. Induction of the bypass phenotype by chlorate treatment. Chlorate was applied to exposed brains (stage 35/36 to 40) to inhibit the sulfation of endogenous HS. (A) Control projection crosses the diencephalon/midbrain boundary (dashed line anteriorly) to enter the anterior tectum (Tec). (B) Projection exposed to 30 mM of chlorate veers abnormally around the anterior border of the tectum and extends dorsally within the diencephalon. (C) Dose-response curve for the bypass phenotype induced with chlorate. The number of embryos exhibiting the phenotype is plotted as a percentage of the total number of embryos in each condition. Numbers in parentheses indicate total number of embryos per experimental condition.