Distribution of Zic proteins in mouse meningeal membrane. Mouse sections were derived from coronal sections through the forebrain at embryonic day 12.5, E12.5 (A, E), embryonic day 14.5, E14.5 (B, C, F, G) or 12 weeks after birth, P12w (D, H). Images (A, E), (B, F) and (C, G) indicate the same regions respectively. Image in (H) is a higher magnification of the boxed region in (D). Immunostaining with CXY2 (A, B, D, H), CXY2/vimentin (E, F), and CXY2/CS56 (C), and differential interference contrast image (G) are shown. Zic signals are indicated by red in (A--C, E, F), and brown in (D, H). The colour green indicates CS56 (C) and vimentin (E, F) immunoreactivities. In (C), the ZIC-like and CS56 immunoreactivities overlapped within the arachnoid layer that expresses vimentin; whereas, only CS56--positive signals were detected within the chondrogenic area, between the two broken lines. The white line indicates the interface between meningeal tissue and cerebral cortex. CS56--positive signals were detected in the region that forms the basal lamina (asterisks). In the adult mouse brain, Zic proteins were still produced in the meningeal cells, as well as the lateral septal nucleus, medial septal nucleus, and diagonal band (D). The positive signals were detected in the arachnoid and perivascular cells (H). a, arachnoid layer; ch, chondrogenic region (prospective temporal bone); ctx, cerebral cortex; db, diagonal band; ls, lateral septal nucleus; ms, medial septal nucleus; v, vessel. Thick scale bar, 1 mm; thin scale bar, 100 μm.