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Fig. 1. Developmental expression of XDmrt4 by whole-mount in situ hybridization. (A) XDmrt4 expression at the early neurula stage is detected at the anterior edge of the neural plate. (B–D) Six1 (B), Xdlx5 (C), and XBF1 (D) expression at a similar stage are shown for comparison. (E) Early neurula stage embryo stained with both XDmrt4 and Six1 probes show that XDmrt4 is expressed in a subdomain of the preplacodal ectoderm. The arrowhead indicates the posterior boundary of XDmrt4, and the arrow marks the posterior domain of Six1. (F and G) Comparison of XDmrt4 (F) and Pax6 (G) expression in sibling embryos illustrates that both genes are expressed in the presumptive olfactory placode (arrowheads). (H and I) Double in situ hybridization showing the relationship of the expression domain of the neural crest-specific gene Slug and XDmrt4 at stage 17. The arrowheads indicate the posterior and anterior boundary of XDmrt4 and Slug, respectively. Views are dorsal-anterior (A–D and F–H) and lateral (E and I, anterior to right). (J) At stage 23, XDmrt4 is detected bilaterally in the prospective nasal placode (arrowheads), anterior view. (K–M) By stages 29/30 XDmrt4 is strongly detected in the developing olfactory organ and the telencephalon (arrowheads). At this stage XDmrt4 is also detected in the foregut (arrows, K and L). Lateral (K) and anterior (M) views, dorsal to top. (L) Transverse section. (N and O) In stage-35 embryos XDmrt4 expression domains in the telencephalon (arrows) and the olfactory organ (arrowheads) are segregated. (N) Dorsal view, anterior to right. (O) Longitudinal section through the olfactory epithelium and the telencephalon. (P–S) At stage 45, XDmrt4 expression persists in the olfactory epithelium (arrowheads, P), the olfactory bulb (arrowheads, Q), and forebrain (arrows, R and S). Whole-brain lateral (Q) and dorsal (R) views. (S) Transverse section through the forebrain. (T) XDmrt4 is also strongly expressed in the gall bladder (arrow) and more diffusely throughout the intestine. (Magnifications: ×10 in A–D, H, and I; ×12 in E, F, and J–N; ×20 in O and S; and ×15 in P, Q, and T.) |
