IN MIGRATING FIBROBLASTS, RECYCLING RECEPTORS ARE CONCENTRATED IN NARROW TUBULES IN THE PERICENTRIOLAR AREA, AND THEN ROUTED TO THE PLASMA-MEMBRANE OF THE LEADING LAMELLA

By following the intracellular processing of recycling transferrin receptors and the selective sorting of a-2 macroglobulin in chick embryo fibroblasts, we have shown that the concentration of 60 nm diam tubules which surrounds the centrioles represents a distal compartment on the recycling pathway. In migrating cells transferrin receptor tracers can be loaded into this compartment and then chased to the cell surface. When they emerge the recycling transferrin receptors are distributed over the surface of the leading lamella.