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Fig. 5. Xcad3 is transiently expressed in the posterior notochord and is a candidate marker for the C region. (A) Whole mount in situ hybridisation of a stage 13 embryo with part of the neural plate removed to show Xcad3 expression (dark staining) in the underlying posterior notochord. View from posterior with dorsal up. (B) Xcad3 in situ hybridisation to a posterior transverse section of an embryo at stage 13 to show presence of transcripts in the neural plate and to a lesser extent in the notochord. Scale bar, 100 mm. (C) Xcad3 expression in the stage 30 tail bud is restricted to the neural tube and posterior wall. Transcripts are absent from the chordoneural hinge and notochord. Scale bar, 250 mm. (D) Schematic diagram to show Xcad3 expression based on (C). Marks E, F and G indicate the relative positions of the transverse sections in (E), respectively. (E) transverse section through tail tip at stage 30 and schematic showing peripheral expression of Xcad3 at a level posterior to the chordoneural hinge. (F) Transverse section and schematic midway through the tail at stage 30 showing restriction of Xcad3 transcripts to the dorsal and lateral periphery. (G) Transverse section through the posterior trunk at the level of the proctodaeum
showing Xcad3 in the neural tube and a few cells of the adjacent somite. Expression in the neural tube is excluded from the floor plate and neural crest derived fin mesenchyme and forms a posterior to anterior gradient. Scale bar in (E), 100 mm. Abbreviations: cnh, chordoneural hinge; end, endoderm; me, fin mesenchyme; nc, notochord; nt, neural tube; pw, posterior wall; s, somite. |
