A role for fibronectin in the migration of avian precardiac cells. II. Rotation of the heart-forming region during different stages and its effects.

Precardiac cells in early chick embryos between stages 5 and 8 of development migrate anteriorly and medially from two well-defined, lateral heart-forming regions to the lateral walls of the developing anterior intestinal portal. Previously, it was shown that an increasing fibronectin (FN) concentration exists at the endoderm-mesoderm interface along the pathway in which the cells move. Thus, a haptotactic mechanism for precardiac cell migration was suggested. To analyze fibronectin's role further the FN concentration difference was interrupted by microsurgically rotating both the precardiac region mesoderm and endoderm (ectoderm was left intact) and by perturbation with the use of an antibody to fibronectin. These experiments, reported here, indicated that precardiac cells do follow cues established by a FN concentration difference at the mesoderm-endoderm interface in the lateral region and that anti-fibronectin can inhibit normal cell migration during heart formation.