Phylogenetic Origins of Brain Organisers

Figure 1

Expression of patterning genes and topography of secondary organisers in four deuterostome lineages. (a) Vertebrate neural tube, (b) ascidian nerve cord, (c) amphioxus nerve cord, and (d) Saccoglossus kowalevskii larva. ANR: anterior neural ridge, C: collar, FB: forebrain, FMB: forebrain-midbrain boundary, HB: hindbrain, MB: midbrain, MHB: midbrain-hindbrain boundary, NC: notochord, P: proboscis, PNT: posterior neural tube, PP: prechordal plate, SC: spinal cord, SV: sensory vesicle, T: trunk, and ZLI: zona limitans intrathalamica. Signalling centres express Bmps and Wnts (green), Fgfs (red) or Hh (blue); arrows indicate that a signalling function has been experimentally demonstrated. For gene names and references see text.

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