Glial bundle formation in spinal roots following experimental neuronopathy.

Spinal motor neurons and dorsal root ganglion cells were caused to degenerate by axoplasmic transport of toxic lectins via the sciatic nerve. Within a few months, loss of axons and glial bundle formation were seen in the proximal portions of the L4-6 ventral and dorsal roots. The glial bundles observed were structurally the same as those described in humans, but they were occasionally also invested with Schwann cell cytoplasmic processes, the cell membrane of which was directly apposed to that of astrocytes. Basal lamina surrounding the outer surface of the bundles was shared by these two as a continuous sheet. This unique complex of astroglial and Schwann cell processes, completely covered by basal lamina, may be a newly formed interface between the central and peripheral nervous systems and thus may severe as a guide and potential pathway for regenerating neurites.