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Fig. 2. Hedgehog target genes. Embryonic stage is indicated in the top right of each panel. Unilaterally injected embryos (the injected half of the embryo, identified via fluorescent lineage tracer, is oriented towards the top in all dorsal views) were fixed and processed at stages 17/18 (left), stage 21/22 (center), or stage 29/30 (right). Ectopic ectodermal hh has only a modest effect on the pronephros at stage 17/18, but by stage 21/22 expression of all markers of the pronephric tubule primordium are extinguished. Marker gene expression in other tissues is not affected, despite equivalent exposure to the hh (blue arrows). Black arrows indicate normal pronephric staining, whereas white arrows indicate abnormal and red arrows absent pronephric staining. The white arrow in the glomus at stage 21/22 indicates a more diffuse but still visible crescent staining pattern. wnt4 is only transcribed at extremely low levels in the pronephros at stage 16/17 and so is not shown. All views of stage 17/18 and 21/22 embryos are dorsal with anterior to the left. All stage 29/30 views are lateral, with anterior to the left and dorsal up. The glomus was detected using crescent at stage 17/18 and 21/22, and nephrin at stage 29/30. |
