Fig. 3

shh is required for axial and fkd4 expression in LFP cells. Dorsal views (A–D) and lateral views (E–H) of wild-type (A, C, E, G) and syu^t4 (B, D, F, H) embryos at the pharyngula period labeled with an in situ probe for fkd4 (A, B; blue cytoplasmic staining) or axial (C–H; blue cytoplasmic staining) and stained with the 4D9 antibody against En-like proteins (brown nuclear staining, out of focus); anterior is left. shh function is required for the induction of fkd4 and axial expression in LFP cells (B, D). While fkd4 in syu embryos stains MFP cells also in anterior trunk regions (B) axial transcription in MFP cells close to the tail bud appears normal (F), while older MFP cells maintain only low levels of expression (D, H), indicating a maintenance function of shh on axial expression in MFP cells.