Tight junctions between the axon and Schwann cell during PNS regeneration

WE report here that during PNS regeneration, short focal tight junctions are present at the interface of regenerating axons and Schwann cells in the distal part of the transected nerve. When regrowing axons were seen in the distal segment, focal fusions of axonal and Schwann cell membranes were observed on electron microscopy. Freeze-fracture study showed short arrays of intramembrane particles in the contacting membrane of axons and Schwann cells. Immunohistochemical study revealed the localization of ZO-1 tight junction associated protein at discrete sites of axon-Schwann cell contact. These results suggest that mechanical links of the axon and Schwann cell by means of short tight junctions are involved in axon-Schwann cell contact events during PNS regeneration.