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Fig. 7 chch-compromised cells migrate to the germ ring and become mesoderm in response to Nodal signals. Transplanted MZoep-LacZ cells to the animal hemisphere of a wild-type host remain within the animal hemisphere at shield stage (A) and are observed in anterior neural structures after 24 hpf (A'). Similar behavior was observed for transplanted MZoep-chch-EnR cells in wild-type hosts (B-B'). Similarly, when donor cells express 12.5 pg xFast1-EnR, along with chch-EnR, migration to the margin is blocked and donor cells are observed in anterior neural structures after 24 hpf (D-D'). Together, these results demonstrate that the migration of the chch inhibited cells to the germ ring and acquisition of mesodermal character depends upon Nodal signaling.