Mesoderm cell migration in the vertebrate gastrula

Mesoderm migration across the inner surface of the outer embryonic layer is an essential morphogenetic mechanism in vertebrate gastrulation. Conserved traits of this process are (1) cadherin-dependent cohesion of the mesoderm, and (2) a predominant role for fibronectin in mediating mesoderm cell-substrate interactions. Compared to lower vertebrates, differentiation of the outer substrate-forming cell layer is accelerated in amniotes, providing mesoderm cells with a basement membrane substrate instead of a loose network of extracellular matrix fibrils. Guidance cues which determine the direction of mesoderm migration have been demonstrated in the fibrillar matrix of the amphibian gastrula.