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 f ibers was investigated by immunocytochemistry in the chicken sciatic n erve. The normal unmyelinated fibers exhibited N-cadherin immunoreacti vity on the plasma membranes of axons and Schwann cells where they wer e in contact with each other, while myelinated fibers displayed no imm unoreactivity except at the mesaxon where Schwann cell plasma membrane s were attached to each other. In the regenerating nerves, intense imm unoreactivity was demonstrated on the surface of plasma membranes of a xons and Schwann cells where axon-axon and axon-Schwann cell contacts were made. No immunoreactivity was observed on the plasma membranes wh ere regenerating axons or Schwann cells were in touch with the basal l amina. In addition, it was revealed that some vesicles in the growth c ones had distinct N-cadherin immunoreactivity at the inner limiting me mbrane surface. These findings indicate that N-cadherin may be involve d in the axon-axon and axon-Schwann cell adhesion in the normal unmyel inated as well as regenerating nerve fibers, and also in the attachmen t of Schwann cell processes at the mesaxon of myelinated fibers. In ad dition, these findings suggest that N-cadherin might be, at least in p art, Supplied by fusion of growth cone vesicles with the surface plasm a membranes in growing axons.