Cervical cord neurons labeled by horseradish peroxidase application to the sciatic nerve in the rat.

After horseradish peroxidase (HRP) application to the proximal cut end of the sciatic nerve in rats aged 3-10 days, HRP-labeled neuronal cell bodies were found ipsilaterally in the ventrolateral region of the ventral horn in the cervical enlargements of the spinal cord. Such labeled neurons were occasionally seen in rats aged 15 days, but not seen at all in rats aged 60-90 days. The labeling was presumably the result of a retrograde transneuronal axonal transport of HRP applied to the sciatic nerve.