Fig. 2

hoxb1a(β-globin):eGFP^um8 transgenic embryos express GFP in r4, but are otherwise indistinguishable from non-transgenic siblings. Embryos were collected at the indicated stages and assayed for expression of hoxb1a (A–C), eGFP (D–F), or krox20 (J–L) by in situ hybridization as well as for eGFP fluorescence (G–I). All embryos are from an outcross of a heterozygous hoxb1a(β-globin):eGFP^um8 carrier. Embryos in D–I are heterozygous for the hoxb1a(β-globin):eGFP^um8 transgene. Embryos in A–C and J–L may be either heterozygous or non-transgenic, but there is no difference in expression of hoxb1a and krox20 within the clutch of embryos. Asterisk in B indicates hoxb1a expression in mesoderm. Arrows in F, H, I indicate eGFP expression in migrating nVII facial motor neurons. All embryos are in dorsal view except G and I, which are lateral views. Anterior is to the top (A, B, D, E, J, K) or to the left (C, F, G, H, I, L).