Fig. 6

Overexpression of ptc1 RNA in wild-type and con^tf18b embryos phenocopies the anteriorised ear phenotype seen in con^tf18b and smu^b641 homozygotes. Lateral views; anterior towards the left, dorsal towards the top. (A,E,I) DIC images of live embryos, focussed at the level of the anterior otolith. Both otoliths in the ears of ptc1-injected embryos (E,I) are small, lateral and ventral, and resemble the anterior otolith of wild-type embryos (A). (B,F,J) Confocal images of FITC-phalloidin stained ears. (B) Wild-type pattern: arrowhead, anterior macula; arrow, posterior macula. A posterior macula is not present on the medial wall of ptc1-injected embryos (F,J). In ears of ptc1 injected wild-type embryos, the anterior macula is present as normal but a second ventral macula is present at the posterior of the ear, as in con (arrowheads, F). In ears of ptc1-injected embryos from a con/+ mating, a single ventral macula covers the ventral surface of the otic vesicle, as in smu ears (arrowhead, J). (C,D,G,H) In situ markers show similar expression patterns in the ears of ptc1-injected embryos and of con and smu. Four cristae may develop (G), and expression of the anterior marker nkx5.1 is expanded (H). We do not have markers that distinguish between con-like and smu-like ears and so these assays were not repeated on ptc1-injected con^tf18b embryos. Scale bars: 50 μm.