Effects of the substratum on the migration of primordial germ cells

It is now clear from work on defined cell types on artificial substrates that various chemical and physical inhomogeneities in the substrates can guide cell locomotion. It is also becoming clear that less well defined inhomogeneities in living cell substrates can guide the normal locomotion of embryonic migratory cells in vivo. The primordial germ cells (p.g.cs) of early anuran amphibian embryos are proving a useful model for the study of cell migration. When isolated from the embryo and cultured on living cellular substrate, p.g.cs become oriented by the shapes of the underlying cells or by their stress fibre cytoskeleton, or both. A combination of scanning and transmission electron microscopy in vivo shows a clearly aligned cellular substrate for p.g.c. migration along part of their route. Furthermore, we find that the glycoprotein fibronectin is involved in p.g.c. adhesion, which suggests a link between orientation of the substrate cells and p.g.c. guidance.