Xenbase Image ID: 145019

Fig. 6. Homology between amphioxus and Xenopus gastrocoel roof plates. Schematics of the gastrocoel roof plates (GRPs) of amphioxus (A,B) and Xenopus (C). Dorsal views of late gastrula (A) and 11.5 h neurula (B) embryos are shown (left) together with transverse sections (right) at the levels indicated. Nodal mRNA expression (blue) in amphioxus becomes asymmetric during early neurulation. Cells that are Nodal positive at late gastrula bud off from the archenteron roof to form the somites. At later stages, the epithelium in between the Nodal-positive cells likewise buds off to become the notochord (not indicated). Drawn according to Yu et al. (Yu et al., 2002). Cilia and flow at the notochordal part of the archenteron are a hypothetical prediction of the authors. (C) Schematic transverse section through a stage 17 Xenopus neurula embryo. Drawn according to Schweickert et al. (Schweickert et al., 2007). Note the striking homology between amphioxus and Xenopus GRPs: in both cases, lateral cells expressing Nodal are fated to become somites while central cells fold off to form (amphioxus) or integrate into (frog) the notochord. no, notochord; np, neural plate; som, somite. Image published in: Blum M et al. (2014) Copyright © 2014. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. Larger Image Printer Friendly View

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