Regeneration of olfactory sensory axons into transplanted segments of peripheral nerve.

Isolated segments of cervical sympathetic trunk were transplanted onto the olfactory mucosa and bulb in adult rats, and olfactory nerve fascicles were sectioned in the region of the transplant. Olfactory axons, presumably arising from newly-formed sensory neurons, were observed to grow into the transplanted segments of peripheral nerve and were ensheathed by Schwann cells of the transplant. The axons were ensheathed as large bundles containing many axons in direct contact, an arrangement characteristic of the normal olfactory nerves, and not of the normal sympathetic trunk. However, single Schwann cell 'units' were each surrounded by basal lamina, an arrangement typical of the sympathetic trunk, not of olfactory nerves. The results indicate that olfactory axons, like other peripheral axons, are capable of directing some aspects of the manner in which they are ensheathed by Schwann cells.