Association of basal lamina with peripheral axons elongating within the rat central nervous system

Using conventional electron microscopic techniques, we examined the sympathetic axons that invade the rat hippocampal formation following cholinergic denervation. We found fascicles of unmyelinated axons adjacent to parenchymal blood vessels. These fascicles were separated from the surrounding neuropil by a duplication of basal lamina. These results suggest that specific morphological changes accompany the invasion of the central nervous system by peripheral axons.