Differentiation of alpha and gamma motoneurons by the retrograde uptake of horseradish peroxidase.

The classification of motoneurons based on size alone may not be an absolute morphological criterion. There appears to be a fair difference in the pattern of horseradish peroxidase uptake between the phrenic and the intercostal motoneurons. Hence we would like to suggest that the gamma and the alpha motoneurons differ in the horseradish peroxidase uptake.