Fig. 4.

MPCs remain responsive to changes in Notch signals after gastrulation. Transiently transgenic cells were transplanted into wild-type host embryos, and transgene expression activated after gastrulation had completed. Activated Notch signaling cell-autonomously promotes hypochord and floor plate fates at the expense of notochord (A), and Notch activity is required for cells to adopt a hypochord fate (B), with changes quantitated (C; raw data and statistics are provided in Table 1). Cell fate changes are statistically significant (see Table 1).