Fig. 1

Fig. 1 Zic2a is required for maintenance, but not for initiation of arx expression in the PT primordium. Embryos were stained by ISH for expression of zic2a (A–C) or arx (D–I). (A) Uninjected embryos express zic2a transiently in the early PT at 4 somites. (B, C) zic2a is not expressed in the PT at 8 and 12 somites. Prethalamus (pt) and thalamus (th) are outlined for reference. (D, E) Normal arx expression in the PT primordium of control MO injected embryos at 4, 8 and 12 somites. (G, H) arx expression in zic2a morphants. (G) arx is expressed normally at 4s (44/50 embryos, 3 exp.). (H) arx is mildly reduced at 8 somites (8/23 embryos, 2 exp.). (I) arx is drastically reduced at 12 somites (28/33 embryos, 2 exp.). (J, K) Representative parasagittal sections of conMO- and zic2aMO-injected embryos stained for arx by ISH at 10s. (L) Graph of average number of arx expressing cells in conMO (n = 3) and zic2aMO-injected (n = 3) embryos (results significant at p = 0.05). All embryos are shown with anterior to the left. Panels A, D and G are dorsal views, all others are lateral views. Arrows mark the PT primordium.