Fig. 11. DM-CPe relationships. (A) Summary of the Gdf7 fate map and ablation studies; color-coding as in Fig. 1, with blue denoting DM or CPe domains with apparent lineage relationships to DM cells. Many mCPe and dCPe cells are derived directly from DM cells. In the telencephalon, DM cell lineages contribute to the anterior tCPe domain, but not to the posterior tCPe (orange). Late Gdf7-mediated ablation results in mCPe and dCPe reduction, but preserved posterior tCPe, consistent with ablation after CPe induction. By contrast, early ablation of Gdf7-expressing DM cells causes near total loss of CPe, including the posterior tCPe. (B) The distinct anterior and posterior tCPe domains; dorsal and medial views, as in Fig. 1. The anterior domain contains DM cell lineages and exhibits marked apoptosis, while the larger posterior domain lacks these features. The two domains are separated by a cryptic boundary located lateral to the di-telencephalic midline boundary. A similar domain structure applies to the adjacent cortical hem. (C) Model of DM-dependent tCPe induction. DM cells are required to establish high-level Bmp signaling in the tCPe anlagen (red). In the anterior domain, both cell-autonomous and non-cell-autonomous mechanisms are involved, whereas posterior domain establishment is non-autonomous. In both domains, homeogenetic mechanisms may be involved (see Discussion for details). Following its establishment, high-level Bmp signaling is then responsible for locally inducing the tCPe (orange) (Hebert et al., 2002).