Fig. 8. Hyoid CNC is generated in moz mutants but forms mispositioned and
misshapen condensations. Confocal micrographs of lateral views of the anterior
pharyngeal arches in live wild-type (A,C,E,G) and moz mutant
(B,D,F,H) embryos (A-F) and larvae (G-H) stained with the vital fluorescent
dye BODIPY-ceramide at 28 hpf, 34 hpf, 48 hpf and 3.5 day stages. Images have
been inverted; the dye fills interstitial spaces, so the inverted images show
cells labeled in white and interstitial space in black. (A,B) Early CNC
appears morphologically indistinguishable from wild type in moz
mutants. Both first and second arches are filled with a cylinder of
postmigratory CNC (Miller et al.,
2000; Kimmel et al.,
2001b), with no obvious defect in hyoid or branchial CNC in
mutants. Other arch tissues also fail to show obvious morphological defects
(C,D). At a slightly later stage the second pharyngeal arch in moz
mutants appears slightly hypoplastic (D), but is still filled with CNC. (E,F)
A day later, condensations have formed in the wild type (E), including in the
second arch a dorsal hyomandibular condensation (arrow, compare with
Fig. 2D) and a ventral
ceratohyal condensation (arrowhead). In moz mutants, no dorsal second
arch hyomandibular condensation is seen and cells appear as lose mesenchyme in
this region (arrow in F). A dorsal mutant condensation does form, in the
position of the wild-type symplectic condensation. The ventral mutant
condensation is mispositioned anteriorly (arrowhead), and is abutting the
first arch ventral condensation. The condensation pattern (E,F) largely
prefigures the resultant larval cartilage pattern (G,H; compare with
Fig. 2D,E). This figure shows
two time points of four different animals: A and C are the same animal, as are
B and D, E and G, and F and H. Arches are numbered in A-D.