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Figure 1. XFGF3 expression in the developing Xenopus embryo. (A) Vegetal view of an early gastrula stage embryo (st. 10.5): dorsal to the top. A faint staining IS detected in a complete ring around the blastopore with higher levels of expression visible dorsally. dl, dorsal blastopore lip. (B) Dorsovegetal view of a late gastrula stage embryo (st. 12.5) showing the periblastoporal expression of XFGF-3. Higher levels of XFGF-3 mRNA are present in the lateral and ventral aspects of the blastopore. Arrowheads point to the anterior stripe of expression that begins to be vIsible at this stage on each side of the neural plate. yp, yolk plug. (C-E) Early neurula stage embryos. (C,E) Dorsal views of a st13 and st 14 embryos, respectively (anterior to the left). Expression in the neural plate has become more prominent by this stage. A faint staining IS detected either side of the midline extending up to the anterior stripe (black arrowhead In C and D).(D) Posterior view of a st. 13 embryo showing XFGF-3 expression around the closed blastopore (bp). (F) Dorsal view of a cleared embryo at the end of the neurula stage (st. 20). The anterior stripe of XFGF-3 expression has become much narrower and has converged towards the midline, (G) Posterior view of a stage 20 embryo showing a strong expression in region lateral to the closed blastopore (bp) extending for some distance along the developing aXIS, (H,I) Tailbud stage embryo (St. 32). (H) Side view of the head region of a cleared embryo showing expression In the branchial arches (bra), in the OtiC vesicle (otv) and at the level of the midbrain/hindbrain junction (mhj). (I) Side view of the posterior region of a cleared embryo showing XFGF-3 expresslon in the tailbud in the chordoneural hinge (cnh) and in the postenor wall (pw) of the neurenteric canal. (J-L) Double whole-mount in situ hybridizations showing XFGF-3 and Krox 20 expression (blue and orange staining. respectively). (J) Early neurula stage embryo (st, 14). Krox 20 and XFGF-3 expression are found to overlap at the level of the prospectIVe rhombomere 3 of the hindbrain. At this stage Krox20 expression In the prospective rhombomere 5 IS only barely detectable (arrowhead), (K) Stage 15 embryo, XFGF-3 at this stage IS expressed in rhombomeres 3-5. (L) Stage 20 embryo. By the end of neurulation the domain of XFGF-3 expression has narrowed, being restricted to the prospectIVe rhombomere 4 (M) Double whole-mount In Situ hybridization showing XFGF-3 and HoxB1 (orange staining) expression In a stage 17 embryo. HoxB1 band of expression identity the prospective rhombomere 4. (N,O) Double whole-mount in situ hybridization showing En-2 (orange staining and XFGF-3 expression. (N) Neurula stage embryo (st. 16). Throughout neurulation the band of XFGF-3 expression lies posterior to that of En-2. (O) Side view of a tailbud stage embryo (Sf. 30). By tailbud stages XFGF-3 expression in the hindbrain has disappeared while a new domain of expressIon has arisen at the isthmus (arrowhead) that overlaps wIth that of En-2 |
