XB-IMG-43553
Xenbase Image ID: 43553
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Fig. 3. Localization of Tcf-1 transcripts containing the beta-catenin binding domain during development of X. tropicalis. Whole-mount in situ hybridizations are shown for stage 7 (A and B), stage 10.5 (C and D), stage 18 (E and F), stage 21 (I), stage 24 (J) and stage 32 (K) X. tropicalis embryos. The probe used corresponds to the N-terminal beta-catenin binding domain of XtTcf-1. (A and B) At blastula stage high levels of Tcf-1 RNA are detected in the animal hemisphere. (B) Section of embryo shown in A, white arrow indicates staining in the roof of the blastocoel. (C) Vegetal and slightly lateral view of a stage 10.5 embryo. XTcf-1 is expressed in the animal cap and most of the marginal zone except for a narrow domain around the (future) blastopore (black arrowhead). (D) Medial view of a sagittally sectioned stage 10.5 embryo; blastopore (black arrowhead), roof of blastocoel (white arrowhead). Expression is high in the sensorial layer of the animal cap and the subepithetial layer of the marginal zone (white arrows) and low in the epithetial layer (black arrows) (Hausen and Riebesell, 1991). Upper and lower parts of the dorsal lip (Ibrahim and Winklbauer, 2001) have low levels of Tcf-1 RNA (open arrowhead), while high levels are present in the subepithelial layer. Anterior involuting mesendoderm (asterisk) is negative. Ventrally, expression of Tcf-1 is high in the subepithelial layer ending in a deep zone at the edge of the blastocoel floor. (E) At stage 18 Tcf-1 transcripts are detected in the neural plate with a discrete anterior border (white arrowhead). A low signal is present at the position of the first visceral arch (black arrowhead; cf. Fig. 3G; Heller and Brändli, 1997). (F) Posterior view of embryo shown in E; expression in the posterior end of the neural plate c.q. neural folds extends ventrally around the blastopore (open arrowhead). (G) Stage 18 embryo stained for XtTcf-1 and XPax-2. The anterior expression of Pax-2 (Heller and Brändli, 1997) overlaps with the anterior border of expression of XTcf-1 (cf. Fig. 3E). (H) Stage 18 embryo stained for XBF-1 (Bourguignon et al., 1998). The expression domain of XBF-1 extends more anteriorly (white arrowhead) than XTcf-1 expression (cf. Figs. 3E,H). (I) Stage 21 embryo, showing staining in the eye (open arrowhead), specific areas of the brain, otic vesicle (red arrowhead), pronephric anlage (white arrowhead) and somites. At later stages, 24 (J) and 32 (K), Tcf-1 continues to be expressed in the eye (open arrowhead), specific areas of the brain, otic vesicle (red arrowhead), branchial arches and head mesenchyme, pronephros (white arrowhead), pronephric duct (black arrowhead), somites and tailbud. Inset in Fig. 3J shows a close-up view of Tcf-1 expression in the pronephric duct (at the level of the black arrowhead). c.g., cement gland. Image published in: Roël G et al. (2003) Copyright © 2003. Image reproduced with permission of the Publisher, Elsevier B. V.
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