Localization of N-cadherin in the normal and regenerating nerve fibers of the chicken peripheral nervous system.

The localization of N-cadherin in the normal, and regenerating nerve fibers was investigated by immunocytochemistry in the chicken sciatic nerve. The normal unmyelinated fibers exhibited N-cadherin immunoreactivity on the plasma membranes of axons and Schwann cells where they were in contact with each other, while myelinated fibers displayed no immunoreactivity except at the mesaxon where Schwann cell plasma membranes were attached to each other. In the regenerating nerves, intense immunoreactivity was demonstrated on the surface of plasma membranes of axons and Schwann cells where axon-axon and axon-Schwann cell contacts were made. No immunoreactivity was observed on the plasma membranes where regenerating axons or Schwann cells were in touch with the basal lamina. In addition, it was revealed that some vesicles in the growth cones had distinct N-cadherin immunoreactivity at the inner limiting membrane surface. These findings indicate that N-cadherin may be involved in the axon-axon and axon-Schwann cell adhesion in the normal unmyelinated as well as regenerating nerve fibers, and also in the attachment of Schwann cell processes at the mesaxon of myelinated fibers. In addition, these findings suggest that N-cadherin might be, at least in part, supplied by fusion of growth cone vesicles with the surface plasma membranes in growing axons.