A researcher interested in neural crest cell migration grafts a small segment of anterior neural tube from a quail embryo into the neural tube of a chicken embryo.

As a control, the researcher places quail anterior neural tube cells back into recipient quail embryos. After 2 days, the researcher finds that the quail cells have failed to migrate in the chicken embryo, but they migrate in quail to populate areas of the face. What can the researcher conclude?

Choose the best answer.