Unmyelinated axons in the posterior funiculi.

Electron microscopy of the dorsal funiculus in the rat reveals that most axons in this pathway are unmyelinated. These axons have not previously been counted, nor are they considered in modern studies on the organization of the dorsal funiculus. Because of the importance of this pathway in somatic sensation, it is important to understand that these fibers exist and that they are present in greater numbers than the well-studied myelinated axons.