Differential labeling by horseradish peroxidase of small and large spinal neurons of rats.

Solid horseradish peroxidase (HRP) was applied to the crushed peroneal nerves of rats and its retrograde transport to spinal ganglion cells and spinal motoneurons was examined after varying survival times. Following short (22-39 h) survival times predominantly small sensory and motoneuronal cell bodies contained HRP. Following long intervals (72-96 h), the percentage of labeled large cells increased in both groups of neurons. The differences were more pronounced in sensory than in motoneurons.