Figure 1.

During corticogenesis, Zic genes are expressed by the meningeal cells. A–C, Expression of Zic1 (A), Zic2 (B), and Zic3 (C) mRNAs in coronal sections of the head at E14.5. Zic genes are abundantly expressed in the medial neural tissues and marginal brain. Strong expression of Zic1 and Zic2 in the marginal brain is indicated by asterisks. Expression of Zic2 in the dorsal VZ/SVZ is indicated by arrowheads. cpe, Choroid plexus; he, cortical hem; ncx, neocortex; lge, lateral ganglionic eminence; nr, neural retina; poa, preoptic area; oe, olfactory epithelium; th, thalamus. D, E, Distribution of the Zic proteins was examined using a pan-Zic antibody in coronal sections of the head at E14.5. Rostral (D) and caudal (E) sections are shown. Zic protein expression in the marginal brain is indicated by asterisks. cpe, Choroid plexus; hip, hippocampus; lge, lateral ganglionic eminence; lv, lateral ventricle; nr, neural retina; sep, septum; th, thalamus; III, third ventricle. F–J, Expression of Nid-1 (F), Foxc1 (G), Zic1 (H), Zic2 (I), and Zic3 (J) mRNAs in the marginal brain at E16.5. These genes are commonly expressed by the meningeal cells. Zic1 and Zic2 are additionally found to be expressed by the CR cells in the cortical MZ (arrowheads). mng, Meninges; mz, marginal zone. K, Distribution of the Zic proteins (red) and collagen IV (green) in the marginal brain at E16.5. The nuclei of the cells are stained with 4′,6-diamidino-2-phenylindole (DAPI) (blue). Zic-positive CR cells in the cortical MZ are indicated by arrowheads. Inset shows cultured meningeal cells from E16.5 brain. The meningeal fibroblasts are intensely positive for Zic (red) and collagen IV (green).