Comparison of the developmental time course of nk2.2 expression in the rostral brain with that of shh/vhh-1 and axial. Whole-mount embryos hybridised with antisense RNA to nk2.2, shh/vhh-1, axial or hlx-1. Lateral views (except A,B) are shown with rostral to the left. In DY, the skin, yolk and eyes have been removed. (A,B) Frontal views (with dorsal up) showing nk2.2 expression (arrowheads) at 95% epiboly (9.5h) (A) and bud/1s (10h) stage (B). Dots outline the yolk plug in A. (C) Lateral view of nk2.2 expression at 3 somites (11h) and 5 somites (11.7h). (D) hlx-1 expression in the forebrain of a 5 somites (11.7h) embryo. (E-Y) Comparison of rostral brain expression domains of nk2.2 (E,H,K,N,Q,T,W), shh/vhh-1 (F,I,L,O,R,U,X) and axial (G,J,M,P,S,V,Y) from 5 somites (11.5h) to 44-48h. The arrowheads in E-G indicate a small groove in the mid-diencephalon at which the cephalic flexure will later form. Arrowhead in Q indicates the gap between rostral and caudal nk2.2 expression domains. In V, the embryo was also labelled with an antisense RNA probe to wnt1 which is expressed in cells beneath the epiphysis (Macdonald et al., 1994). Abbreviations: cb, cerebellum; cf, cephalic flexure; e, epiphysis; fp, floorplate; hy, hypothalamus; mb, midbrain; mdb, mid-diencephalic boundary; or, optic recess; p; anlage of the anterior pituitary; rd and cd, rostral and caudal domains of nk2.2 expression; t, telencephalon; te, tegmentum; III, third ventricle. Scale bar=100 μm
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