Figure 4.

Schematic diagram of proepicarial organ quail–chicken chimera experiments. (A) For these experiments, a quail embryo (pink) serves as the donor, and the chicken embryo (blue) is the recipient. (B) The proepicardial organ from the quail donor (pink bubbles, B) is surgically removed and placed at the site of the recipient's proepicardial organ (blue bubbles). (C, D) The chicken recipient is reincubated with the transplanted quail epicardium (pink bubbles), and (E) the proepicaridal organ develops into the epicardium, which then envelops the entire heart (pink bubbles) as it would during normal development.