Fig. 1. Mutations in spiel ohne grenzen (spg) affect MHB formation. (A-E) Wild-type, (F-J) spgm216 and (K-O) spgm793 mutant live (A,F,K) or whole-mount embryos at 24 hours post fertilization (hpf). (B,G,L) otx2 expression in the pretectum and tectum; (C,H,M) fgf8 expression at the midbrain-hindbrain boundary; and (D,I,N) strong zp50 expression in the cerebellum. zp50 is expressed in a complex pattern in all major subdivisions of the brain. (E,J,O) zash1a expression in the tegmentum and ventral hindbrain. Arrows indicate the position of MHB. Arrowheads indicate the limits of zash1a expression in the tegmentum and ventral rhombomere 1. In all embryos, anterior is towards the left and dorsal is upwards. cb, cerebellum; ey, eye; hb, hindbrain; mhb, midbrain-hindbrain boundary; ov, otic vesicle; tc, tectum; te, telencephalon; tg, tegmentum.
