Retrograde transport of the lectin Phaseolus vulgaris leucoagglutinin (PHA-L) by rat spinal motoneurons.

The lectin Phaseolus vulgaris leucoagglutinin (PHA-L) has been used primarily as an anterograde transport tracer in the CNS. We present evidence of PHA-L retrograde transport by rat spinal motoneurons after injection into the triceps brachii. Labelled motoneurons were localized in specific and well-defined neuron pools in the ventral horn. Primary afferent labelling was not seen in the spinal gray matter. Dorsal rhizotomy did not eliminate or decrease motoneuron labelling. The retrograde transport rate was about 8 mm/day. PHA-L can clearly undergo retrograde, as well as anterograde, transport.