The organization of endoneural collegen in peripheral nerves as revealed with the scanning electron microscope.

Transmission electron microscopy of isolated nerve fibers of rat sciatic nerve and scanning microscopy of small groups of fibers reveal that the majority of collagen fibrils form tightly woven cuffs around individual nerve fibers. Only a small fraction of the fibrils is not associated with individual nerve fibers and forms a loose, wide-meshed net between them. These observations reconfirm the pre-electron-microscopic concept of a sheath of Key and Retzius or of Plenk and Laidlaw, respectively.