The ectoderm of swr- embryos is neuralised. In lateral views, dorsal is to the right; in dorsal views, anterior is up. (A,B) Lateral views of gta2 expression (prospective epidermis) in bud stage embryos. (C,D) Lateral views of noi/pax2.1 expression (prospective midbrain) in 1-2 somite stage embryos. (E-F) Dorsal views of hoxb1b (posterior tissue) and krx20 (r3 + r5) in 1-2 somite stage embryos. Scale in this and subsequent figures: the yolk ball of wildtype embryos is 700 μm across. nne, non-neural ectoderm; np, neural plate; r3, rhombomere 3; wt, wild-type.