Fig. 6. (A-F) Comparison of the Otx1 and Svet1 cortical expression at the stage E15.5 in wild type (A,B) and homozygous Sey mutant (D-E). The size of the ventricular zone in the Sey mutant is not affected, as revealed by Otx1 expression (D). The SVZ is enlarged, its morphology is altered and it does not express Svet1 (F), which can be seen only in the cingulate cortex (E). (G-L) Comparison of the Otx1 and Svet1 cortical expression at the stage E18.5 of wild-type (G-I) and Sey mutant (J-L). Deep layer neurons (Otx1-positive cells) are present in the Sey cortical plate (J). Superficial layer neurons (Svet1-positive cells; Otx1/Svet1-negative cells of the cortical plate) are absent in the Sey cortex. Svet1 is not expressed in the SVZ of the Sey cortex (K). Arrowheads in F, K and L mark the lateral limit of Svet1 expression.