Mesaxon

In neurobiology, a mesaxon is a pair of parallel plasma membranes of a Schwann cell, marking the point of edge-to-edge contact by the Schwann cell encircling the axon. A single Schwann cell of the peripheral nervous system will wrap around and support only one individual axon (then myelinated; ratio of 1:1), while the oligodendrocytes found in the central nervous system can wrap around and support 5-8 axons. Thin unmyelinated axons are often bundled, with several unmyelinated axons to a single mesaxon (and several such groups to a single Schwann cell).