Fig. 14. Soma (A), neurite (B) and axon diameters (C) of the five classes of motor neurons. (A) FR/W class neurons had significantly larger somata than SA and M neurons. Because the somata of these motor neurons were not perfectly round, the diameter was measured by taking the mean of the smallest diameter and the largest diameter. (B) The F/O class neurons had significantly larger neuritic diameters than all other classes of neurons. We measured neurite diameter at the point just posterior to the junction where the neurite from the soma reaches the main branch. (C) FR/W class neurons had significantly larger diameter axons than FA and M class neurons, and F/O class neurons had significantly larger diameter axons than FA and M class neurons. We measured axon diameter at the point where the neurite exits the neuropil. This location is not ideal since the neurites tend to narrow at this point before becoming larger in diameter in the nerve, but unfortunately not all of our dye-fills included the true axon in the nerve.