Lumbar motoneurons of man: III. The number and diameter distribution of large- and intermediate- diameter cytons by nuclear columns.

In a recent study we estimated the number and frequency distribution of the diameters of the cytons of all of the combined motoneuron columns of L3, L4 and L5 ventral horn of the spinal cord of man. In the present study we have estimated the number and frequency distribution of the diameter of motoneuron cytons in the lateral (L) and the medial (M) groups of the ventral horns of L3, L4 and L5 spinal segments and of the three motoneuron columns [antero-lateral (AL), central (C), and combined postero-lateral and post-postero-lateral )PL + PPL)] of the L group in the L5 segment in the same 18 reference spinal cords of the earlier study. These reference morphometric values are needed to be able to determine whether the number and size of motoneuron cytons are abnormal or not, and in what way are they abnormal, in various neuromuscular diseases.