Fig. 8. Model of transcriptional regulation of VM-metameric genes during stages 10-11. Ventrolateral view of VM is shown schematically. Gray strip, ectodermal cell layer. Green and brown-outlined boxes, ectodermal WG and HH sources, respectively. Blue horizontal arrows in the top diagram show the posterior expansion of the VM competent region; black arrows indicate activation; black-T-shaped-lines indicate repression. WG and HH susceptible regions are shown by colored lines along the future VM. tin/bnl/bap (green), VM-hh (yellow) and con (crimson) expression are indicated. Reduced con expression at the anterior end of VM-PSs is indicated in pink. For simplicity, three gene groups are separately depicted in three successive VM-PSs. See the text for details.