Fig. 1.

Comparison of Spry1, Spry2, and Wnt reporter expression domains from PPR to otic placode stages. In situ hybridization analysis of Spry1 and Spry2 expression domains compared to Wnt reporter activity in TCF/Lef-lacZ embryos at the stages indicated. Transverse sections are shown, dorsal oriented to the top. a – c Spry1 expression, Spry2 expression, and TCF/Lef-lacZ reporter activity at early somite stages in the posterior PPR. Arrowhead indicates the presumptive otic/epibranchial region. Little or no TCF/Lef-lacZ reporter activity is detected in the posterior PPR at this stage (c). (d – f’) Spry1 expression, Spry2 expression, and TCF/Lef-lacZ reporter activity in anterior (d – f) and posterior (d’ – f’) transverse sections through the OEPD. The entire OEPD is bracketed. (g – i”) Spry1 expression, Spry2 expression, and TCF/Lef-lacZ reporter activity in anterior (g – i), medial (g’ – i’), and posterior (g” – i”) transverse sections through the otic placode (bracketed). Abbreviations: neural ectoderm (ne), endoderm (ed), hindbrain (hb). Scale bar, 50 μm