Fig. 6

Fig. 6 ntl^- partially suppresses the flh^- floor plate defect. Side views, with anterior to the left. The left panels show matched left side views, with dorsal to the top. The right panels show dorsal views at higher magnification. RNA in situ hybridization for shh (Krauss et al., 1993). In wild-type embryos (A, B), a one-cell-wide row of floor plate is labeled along the length of the trunk and tail (arrowheads). The floor plate is disrupted into islands of cells in flh mutants (C, D; 8 of 50 flh mutants had more significant stretches of continuous floor plate labeling than in the example shown). In ntl mutant floor plate is present along most of the length of the trunk, except for the caudalmost region (last 1 – 3 somites, E; we also observed caudal plate to be forked in about half the ntl mutants, and interrupted caudally in 8 of 50). The ntl mutant floor plate is 3 – 4 cells wide (F). Floor plate is present along most of the trunk in flh;ntl double mutants. Compared with ntl mutants, the caudal disruption of the floor plate is more extensive in the flh;ntl double mutant (floor plate is lacking in the caudalmost 4 – 8 somites (G). We also observe local regions along the trunk where the floor plate is disrupted in individual double mutants (not shown). Otherwise, shh labeling in flh;ntl double mutants is generally ntl^--like, including substantial floor plate widening (H). We observed the same floor plate phenotypes in these mutants with the marker col2a1 (data not shown). Scale bars, 100 um (left panels), 25 um (right panels).