Fig. 8

Overexpression of shh and dnPKA RNA in wild-type embryos results in posteriorised ears. (A-K) Lateral views; anterior towards the left, dorsal towards the top. (L-O) Dorsal views; anterior towards the left, lateral towards the top. (A-C) DIC images of live ears. Scale bars: 50 μm. The ears of shh- and dnPKA-injected embryos are small and contain either a single otolith (arrowhead, B) or fused otoliths (arrowhead, C), positioned medially. A ventral anterior macula (arrow, A) is absent in these posteriorised ears. (D-F) Confocal images of FITC-phalloidin stains showing the pattern of sensory hair cell stereocilia in posterior maculae. Scale bars: 25 μm. (D) Wild-type pattern. The posterior macula has a rounded posterior region and a slim anterior projection (D). Posterior maculae of dnPKA-and shh-injected embryos have two rounded posterior ends resulting in a `butterfly′ (E) or `bow-tie′ (F) shape. Note that both phenotypes shown in B,C,E,F could be caused by either shh or dnPKA RNA injection. (G-O) In situ hybridisation performed on shh-injected embryos. Scale bars: 50 μm. (G-I) Posterior follistatin exprcssion is either duplicated at the anterior of the otic vesicle or extends medially along the length of the otic vesicle in posteriorised ears (arrows). (J,K) Anterior nkx5.1 expression is reduced to a small central domain in posteriorised ears. (L-O) Anterior fgf8 and pax5 expression is absent from posteriorised ears.