Fig. 1. Svet1 RNA distribution in developing cortex. (A,B,D,E,G,H,M,N,P,Q) dark field; (C,F,I.O,R) bright field. Svet1 expression begins in the SVZ immediately after its first appearance in the rostrolateral cortex (B). The arrowhead in C indicates the transition between the rostral part of the cortex where the SVZ has just begun to form and the caudal part where there is no SVZ yet. The dashed line in C denotes the boundary between SVZ and VZ, which coincides with that of Svet1 expression. (D-R) Comparison of Otx1 and Svet1 expression in the E13.5 (D-L) and E15.5 (M-R) cortex. Otx1 is expressed in the cells of the cortical ventricular zone of both E13.5 (D,G,J) and E15.5 (M,P). In the cortex of E15.5 embryos, Otx1 is expressed in the cortical plate and intermediate zone. Note that in P and Q the expression of Otx1 is at similar levels in the SVZ and IZ, while Svet1 is confined to the SVZ only. I and R are high magnification views of the regions boxed in F and O. The dashed line in R demarcates the boundary between SVZ and VZ, which coincides with the boundary between Svet1 and Otx1 expression. (J,K) High power view of the region boxed in F. Arrowheads show the lower limit of Svet1 (K) and upper limit of Otx1 (J) expression. Left sides of J and K have been digitally contrasted by means of Adobe Photoshope software in order to demonstrate silver grain density more clearly. (L) Immunohistochemistry with anti-BrdU antibody on an adjacent section. The dashed line denotes the approximate boundary between the VZ an SVZ (svz + iz according to Altman and Bayer). The cortical region is the same as indicated by the box in F. BN, basal nuclei; cp, cortical plate; HIP, hippocampus; iz, intermediate zone; NC, neocortex; pl, primordial plexiform layer; SEP, septum; Th, thalamus. Bar in F, 100 µm.
