The localization of laminin and fibronectin on the Schwann cell basal lamina.

The localization of laminin and fibronectin was examined on the basal laminae of Schwann cells. Basal laminae from sciatic nerves were isolated by sonication, and the localization of laminin and fibronectin on such isolated basal laminae was studied by immunoferritin histochemistry. Laminin was localized mainly on the cellular side (i.e. the side originally facing the Schwann cell plasma membrane) of the basal laminae. On the other hand, fibronectin was found to be present as aggregates only on the interstitial side (i.e., the side originally facing the endoneurial connective tissue) of the basal laminae. Thus, the locations of laminin and fibronectin were distinctly different. It is presumed that laminin might be involved in the attachment of axons and Schwann cells to the basal laminae, while fibronectin mediates the adhesion of the basal laminae to connective tissue elements, including the collagen fibrils. These findings are discussed from a standpoint of nerve regeneration through the basal laminae scaffolds of Schwann cells.