Distribution of particle aggregates in the internodal axolemma and adaxonal Schwann cell membrane of rodent peripheral nerve.

Freeze-fracture studies on myelinated fibres from the internodal regions of rat and mouse sciatic nerve show symmetrical particle aggregates within the adaxonal Schwann cell plasmalemma and particle clusters in the axolemma. These are mainly confined to the vicinity of the internal mesaxon and the Schmidt-Lanterman incisures. The Schwann cell particle aggregates are concentrated as bands over the cytoplasmic pockets of Schmidt-Lanterman incisures and the paramesaxonal pockets. In the axolemma there are linear rows of particle aggregates along the groove related to the inner mesaxon and in bands to either side of it. The morphological features suggest the possibility of metabolic coupling between the axoplasm and the Schwann cell cytoplasm via the periaxonal space.